Schedule III - Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	$ 708,831
Initial Costs
Land	553,388
Buildings & Improvements	2,617,102
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	3,271,718
Total Costs
Land	553,388
Buildings & Improvements	5,888,820
Total	6,442,208	[1]
Accumulated Depreciation	(952,106)	[2]
Net Cost Basis	5,490,102
Unamortized discount	1,776
Secured notes payable	708,831		716,144
Term of operating lease obligation related to office leases	6 years
Alexandria Center™ at Kendall Square
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	72,454
Buildings & Improvements	191,904
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	244,342
Total Costs
Land	72,454
Buildings & Improvements	436,246
Total	508,700	[1]
Accumulated Depreciation	(30,643)	[2]
Net Cost Basis	478,057
Alexandria Technology Square®
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	208,457	[3]
Initial Costs
Land	0
Buildings & Improvements	619,658
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	166,260
Total Costs
Land	0
Buildings & Improvements	785,918
Total	785,918	[1]
Accumulated Depreciation	(121,028)	[2]
Net Cost Basis	664,890
Unamortized discount	226
480 Arsenal Street
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	6,413
Buildings & Improvements	5,457
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	46,055
Total Costs
Land	6,413
Buildings & Improvements	51,512
Total	57,925	[1]
Accumulated Depreciation	(12,884)	[2]
Net Cost Basis	45,041
780/790 Memorial Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	0
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	44,894
Total Costs
Land	0
Buildings & Improvements	44,894
Total	44,894	[1]
Accumulated Depreciation	(16,754)	[2]
Net Cost Basis	28,140
500 Arsenal Street
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	3,360
Buildings & Improvements	7,316
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	28,807
Total Costs
Land	3,360
Buildings & Improvements	36,123
Total	39,483	[1]
Accumulated Depreciation	(12,473)	[2]
Net Cost Basis	27,010
167 Sidney Street/99 Erie Street
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	0
Buildings & Improvements	12,613
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	11,772
Total Costs
Land	0
Buildings & Improvements	24,385
Total	24,385	[1]
Accumulated Depreciation	(3,439)	[2]
Net Cost Basis	20,946
79/96 Thirteenth Street Charlestown Navy Yard
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	4,696	[4]
Initial Costs
Land	0
Buildings & Improvements	6,247
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	8,640
Total Costs
Land	0
Buildings & Improvements	14,887
Total	14,887	[1]
Accumulated Depreciation	(2,404)	[2]
Net Cost Basis	12,483
Alexandria Park at 128
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	23,919	[4],[5]
Initial Costs
Land	8,514
Buildings & Improvements	31,863
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	62,255
Total Costs
Land	8,514
Buildings & Improvements	94,118
Total	102,632	[1]
Accumulated Depreciation	(24,939)	[2]
Net Cost Basis	77,693
19 Presidential Way
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	12,833
Buildings & Improvements	27,333
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	64
Total Costs
Land	12,833
Buildings & Improvements	27,397
Total	40,230	[1]
Accumulated Depreciation	(5,936)	[2]
Net Cost Basis	34,294
100 Beaver Street
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,257
Buildings & Improvements	7,755
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	12,458
Total Costs
Land	1,257
Buildings & Improvements	20,213
Total	21,470	[1]
Accumulated Depreciation	(3,650)	[2]
Net Cost Basis	17,820
285 Bear Hill Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	422
Buildings & Improvements	3,538
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	5,348
Total Costs
Land	422
Buildings & Improvements	8,886
Total	9,308	[1]
Accumulated Depreciation	(110)	[2]
Net Cost Basis	9,198
111/130 Forbes Boulevard
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	3,146
Buildings & Improvements	15,725
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	2,932
Total Costs
Land	3,146
Buildings & Improvements	18,657
Total	21,803	[1]
Accumulated Depreciation	(3,526)	[2]
Net Cost Basis	18,277
20 Walkup Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	2,261
Buildings & Improvements	7,099
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	9,028
Total Costs
Land	2,261
Buildings & Improvements	16,127
Total	18,388	[1]
Accumulated Depreciation	(1,281)	[2]
Net Cost Basis	17,107
306 Belmont Street & 350 Plantation Street
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,806
Buildings & Improvements	11,696
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	1,778
Total Costs
Land	1,806
Buildings & Improvements	13,474
Total	15,280	[1]
Accumulated Depreciation	(3,255)	[2]
Net Cost Basis	12,025
30 Bearfoot Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,220
Buildings & Improvements	22,375
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	44
Total Costs
Land	1,220
Buildings & Improvements	22,419
Total	23,639	[1]
Accumulated Depreciation	(4,951)	[2]
Net Cost Basis	18,688
Alexandria Center™ for Science & Technology
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	62,074
Buildings & Improvements	145,303
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	271,071
Total Costs
Land	62,074
Buildings & Improvements	416,374
Total	478,448	[1]
Accumulated Depreciation	(41,141)	[2]
Net Cost Basis	437,307
Alexandria Technology Center - Gateway
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	100,019	[6]
Initial Costs
Land	45,425
Buildings & Improvements	121,059
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	13,965
Total Costs
Land	45,425
Buildings & Improvements	135,024
Total	180,449	[1]
Accumulated Depreciation	(31,487)	[2]
Net Cost Basis	148,962
249/259 East Grand Avenue
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	46,013
Initial Costs
Land	14,289
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	119,463
Total Costs
Land	14,289
Buildings & Improvements	119,463
Total	133,752	[1]
Accumulated Depreciation	(10,418)	[2]
Net Cost Basis	123,334
400/450 East Jamie Court
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	0
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	107,039
Total Costs
Land	0
Buildings & Improvements	107,039
Total	107,039	[1]
Accumulated Depreciation	(10,654)	[2]
Net Cost Basis	96,385
500 Forbes Boulevard
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	38,911
Buildings & Improvements	75,337
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	13,604
Total Costs
Land	38,911
Buildings & Improvements	88,941
Total	127,852	[1]
Accumulated Depreciation	(14,240)	[2]
Net Cost Basis	113,612
7000 Shoreline Court
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	31,835	[6]
Initial Costs
Land	7,038
Buildings & Improvements	39,704
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	7,107
Total Costs
Land	7,038
Buildings & Improvements	46,811
Total	53,849	[1]
Accumulated Depreciation	(10,531)	[2]
Net Cost Basis	43,318
341/343 Oyster Point Boulevard
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	6,127
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	31,487
Total Costs
Land	6,127
Buildings & Improvements	31,487
Total	37,614	[1]
Accumulated Depreciation	(12,833)	[2]
Net Cost Basis	24,781
849/863 Mitten Road & 866 Malcolm Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	3,211
Buildings & Improvements	8,665
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	15,130
Total Costs
Land	3,211
Buildings & Improvements	23,795
Total	27,006	[1]
Accumulated Depreciation	(7,510)	[2]
Net Cost Basis	19,496
2425 Garcia Avenue & 2400/2450 Bayshore Parkway
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	847
Initial Costs
Land	1,512
Buildings & Improvements	21,323
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	23,763
Total Costs
Land	1,512
Buildings & Improvements	45,086
Total	46,598	[1]
Accumulated Depreciation	(15,265)	[2]
Net Cost Basis	31,333
3165 Porter Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	20,873	[5]
Initial Costs
Land	0
Buildings & Improvements	19,154
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	2,088
Total Costs
Land	0
Buildings & Improvements	21,242
Total	21,242	[1]
Accumulated Depreciation	(5,146)	[2]
Net Cost Basis	16,096
75/125 Shoreway Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	6,617
Buildings & Improvements	7,091
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	10,432
Total Costs
Land	6,617
Buildings & Improvements	17,523
Total	24,140	[1]
Accumulated Depreciation	(2,718)	[2]
Net Cost Basis	21,422
3350 West Bayshore Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	4,800
Buildings & Improvements	6,693
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	10,681
Total Costs
Land	4,800
Buildings & Improvements	17,374
Total	22,174	[1]
Accumulated Depreciation	(3,030)	[2]
Net Cost Basis	19,144
2625/2627/2631 Hanover Street
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	0
Buildings & Improvements	4,014
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	15,134
Total Costs
Land	0
Buildings & Improvements	19,148
Total	19,148	[1]
Accumulated Depreciation	(7,037)	[2]
Net Cost Basis	12,111
ARE Nautilus
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	6,683
Buildings & Improvements	27,600
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	81,621
Total Costs
Land	6,683
Buildings & Improvements	109,221
Total	115,904	[1]
Accumulated Depreciation	(22,200)	[2]
Net Cost Basis	93,704
ARE Sunrise
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	19,841	[7]
Initial Costs
Land	2,768
Buildings & Improvements	15,491
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	41,360
Total Costs
Land	2,768
Buildings & Improvements	56,851
Total	59,619	[1]
Accumulated Depreciation	(28,685)	[2]
Net Cost Basis	30,934
ARE Spectrum
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	19,576
Buildings & Improvements	78,438
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	3,958
Total Costs
Land	19,576
Buildings & Improvements	82,396
Total	101,972	[1]
Accumulated Depreciation	(13,290)	[2]
Net Cost Basis	88,682
11119 North Torrey Pines Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	9,994
Buildings & Improvements	37,099
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	32,744
Total Costs
Land	9,994
Buildings & Improvements	69,843
Total	79,837	[1]
Accumulated Depreciation	(4,364)	[2]
Net Cost Basis	75,473
5200 Illumina Way
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	24,607
Buildings & Improvements	96,606
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	68,719
Total Costs
Land	24,607
Buildings & Improvements	165,325
Total	189,932	[1]
Accumulated Depreciation	(10,887)	[2]
Net Cost Basis	179,045
10300 Campus Point Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	17,945
Buildings & Improvements	86,645
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	98,089
Total Costs
Land	17,945
Buildings & Improvements	184,734
Total	202,679	[1]
Accumulated Depreciation	(8,021)	[2]
Net Cost Basis	194,658
ARE Esplanade
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	11,598	[7]
Initial Costs
Land	6,309
Buildings & Improvements	26,925
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	47,215
Total Costs
Land	6,309
Buildings & Improvements	74,140
Total	80,449	[1]
Accumulated Depreciation	(7,510)	[2]
Net Cost Basis	72,939
ARE Towne Centre
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	34,866	[5]
Initial Costs
Land	853
Buildings & Improvements	26,861
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	18,401
Total Costs
Land	853
Buildings & Improvements	45,262
Total	46,115	[1]
Accumulated Depreciation	(24,260)	[2]
Net Cost Basis	21,855
9880 Campus Point Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	3,900
Buildings & Improvements	16,165
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	20,048
Total Costs
Land	3,900
Buildings & Improvements	36,213
Total	40,113	[1]
Accumulated Depreciation	(7,914)	[2]
Net Cost Basis	32,199
5810/5820/6138/6150 Nancy Ridge Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	11,689	[5]
Initial Costs
Land	3,913
Buildings & Improvements	20,496
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	11,760
Total Costs
Land	3,913
Buildings & Improvements	32,256
Total	36,169	[1]
Accumulated Depreciation	(7,039)	[2]
Net Cost Basis	29,130
ARE Portola
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	6,476
Buildings & Improvements	23,327
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	20,039
Total Costs
Land	6,476
Buildings & Improvements	43,366
Total	49,842	[1]
Accumulated Depreciation	(3,873)	[2]
Net Cost Basis	45,969
10121/10151 Barnes Canyon Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	0
Buildings & Improvements	5,100
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	0
Total Costs
Land	0
Buildings & Improvements	5,100
Total	5,100	[1]
Accumulated Depreciation	0	[2]
Net Cost Basis	5,100
7330 Carroll Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	4,655	[4]
Initial Costs
Land	2,650
Buildings & Improvements	19,878
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	1,145
Total Costs
Land	2,650
Buildings & Improvements	21,023
Total	23,673	[1]
Accumulated Depreciation	(1,805)	[2]
Net Cost Basis	21,868
5871 Oberlin Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	6,485	[8]
Initial Costs
Land	1,349
Buildings & Improvements	8,016
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	3,529
Total Costs
Land	1,349
Buildings & Improvements	11,545
Total	12,894	[1]
Accumulated Depreciation	(650)	[2]
Net Cost Basis	12,244
Unamortized discount	39
6146/6166 Nancy Ridge Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,248
Buildings & Improvements	3,839
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	4,970
Total Costs
Land	1,248
Buildings & Improvements	8,809
Total	10,057	[1]
Accumulated Depreciation	(5,462)	[2]
Net Cost Basis	4,595
11025/11035/11045 Roselle Street
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,672
Buildings & Improvements	8,709
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	12,846
Total Costs
Land	1,672
Buildings & Improvements	21,555
Total	23,227	[1]
Accumulated Depreciation	(5,172)	[2]
Net Cost Basis	18,055
3985 Sorrento Valley Boulevard
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	7,570	[9]
Initial Costs
Land	2,422
Buildings & Improvements	15,456
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	445
Total Costs
Land	2,422
Buildings & Improvements	15,901
Total	18,323	[1]
Accumulated Depreciation	(1,296)	[2]
Net Cost Basis	17,027
Unamortized discount	90
10505 Roselle Street & 3770 Tansy Street
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,094
Buildings & Improvements	3,074
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	3,881
Total Costs
Land	1,094
Buildings & Improvements	6,955
Total	8,049	[1]
Accumulated Depreciation	(5,014)	[2]
Net Cost Basis	3,035
13112 Evening Creek Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	12,557	[7]
Initial Costs
Land	7,393
Buildings & Improvements	27,950
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	150
Total Costs
Land	7,393
Buildings & Improvements	28,100
Total	35,493	[1]
Accumulated Depreciation	(4,759)	[2]
Net Cost Basis	30,734
Alexandria Center™ for Life Science
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	0
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	516,879
Total Costs
Land	0
Buildings & Improvements	516,879
Total	516,879	[1]
Accumulated Depreciation	(32,334)	[2]
Net Cost Basis	484,545
100 Phillips Parkway
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	9,640	[4]
Initial Costs
Land	1,840
Buildings & Improvements	2,298
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	14,807
Total Costs
Land	1,840
Buildings & Improvements	17,105
Total	18,945	[1]
Accumulated Depreciation	(7,534)	[2]
Net Cost Basis	11,411
102 Witmer Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,625
Buildings & Improvements	19,715
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	5,641
Total Costs
Land	1,625
Buildings & Improvements	25,356
Total	26,981	[1]
Accumulated Depreciation	(5,434)	[2]
Net Cost Basis	21,547
701 Veterans Circle
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,468
Buildings & Improvements	7,885
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	24
Total Costs
Land	1,468
Buildings & Improvements	7,909
Total	9,377	[1]
Accumulated Depreciation	(1,277)	[2]
Net Cost Basis	8,100
5100 Campus Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	327
Buildings & Improvements	2,117
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	1,189
Total Costs
Land	327
Buildings & Improvements	3,306
Total	3,633	[1]
Accumulated Depreciation	(1,169)	[2]
Net Cost Basis	2,464
9800 Medical Center Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	76,000
Initial Costs
Land	5,523
Buildings & Improvements	99,696
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	93,752
Total Costs
Land	5,523
Buildings & Improvements	193,448
Total	198,971	[1]
Accumulated Depreciation	(35,579)	[2]
Net Cost Basis	163,392
1330 Piccard Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	2,800
Buildings & Improvements	11,533
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	28,530
Total Costs
Land	2,800
Buildings & Improvements	40,063
Total	42,863	[1]
Accumulated Depreciation	(11,373)	[2]
Net Cost Basis	31,490
1500/1550 East Gude Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,523
Buildings & Improvements	7,731
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	4,802
Total Costs
Land	1,523
Buildings & Improvements	12,533
Total	14,056	[1]
Accumulated Depreciation	(4,597)	[2]
Net Cost Basis	9,459
14920/15010 Broschart Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	6,006	[10]
Initial Costs
Land	4,904
Buildings & Improvements	15,846
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	3,778
Total Costs
Land	4,904
Buildings & Improvements	19,624
Total	24,528	[1]
Accumulated Depreciation	(2,648)	[2]
Net Cost Basis	21,880
Unamortized discount	91
1405 Research Boulevard
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	899
Buildings & Improvements	21,946
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	11,479
Total Costs
Land	899
Buildings & Improvements	33,425
Total	34,324	[1]
Accumulated Depreciation	(9,183)	[2]
Net Cost Basis	25,141
5 Research Place
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,466
Buildings & Improvements	5,708
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	26,651
Total Costs
Land	1,466
Buildings & Improvements	32,359
Total	33,825	[1]
Accumulated Depreciation	(5,604)	[2]
Net Cost Basis	28,221
9920 Medical Center Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	2,797
Buildings & Improvements	8,060
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	306
Total Costs
Land	2,797
Buildings & Improvements	8,366
Total	11,163	[1]
Accumulated Depreciation	(1,932)	[2]
Net Cost Basis	9,231
5 Research Court
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,647
Buildings & Improvements	13,258
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	5,142
Total Costs
Land	1,647
Buildings & Improvements	18,400
Total	20,047	[1]
Accumulated Depreciation	(7,092)	[2]
Net Cost Basis	12,955
12301 Parklawn Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,476
Buildings & Improvements	7,267
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	462
Total Costs
Land	1,476
Buildings & Improvements	7,729
Total	9,205	[1]
Accumulated Depreciation	(1,719)	[2]
Net Cost Basis	7,486
Alexandria Technology Center - Gaithersburg I
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	10,183
Buildings & Improvements	59,641
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	20,502
Total Costs
Land	10,183
Buildings & Improvements	80,143
Total	90,326	[1]
Accumulated Depreciation	(20,414)	[2]
Net Cost Basis	69,912
Alexandria Technology Center - Gaithersburg II
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	4,531
Buildings & Improvements	21,594
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	29,741
Total Costs
Land	4,531
Buildings & Improvements	51,335
Total	55,866	[1]
Accumulated Depreciation	(19,864)	[2]
Net Cost Basis	36,002
16020 Industrial Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	2,924
Buildings & Improvements	19,664
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	700
Total Costs
Land	2,924
Buildings & Improvements	20,364
Total	23,288	[1]
Accumulated Depreciation	(8,989)	[2]
Net Cost Basis	14,299
401 Professional Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,129
Buildings & Improvements	6,941
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	5,652
Total Costs
Land	1,129
Buildings & Improvements	12,593
Total	13,722	[1]
Accumulated Depreciation	(4,056)	[2]
Net Cost Basis	9,666
950 Wind River Lane
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	2,400
Buildings & Improvements	10,620
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	1,050
Total Costs
Land	2,400
Buildings & Improvements	11,670
Total	14,070	[1]
Accumulated Depreciation	(1,168)	[2]
Net Cost Basis	12,902
620 Professional Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	784
Buildings & Improvements	4,705
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	1,600
Total Costs
Land	784
Buildings & Improvements	6,305
Total	7,089	[1]
Accumulated Depreciation	(1,052)	[2]
Net Cost Basis	6,037
8000/9000/10000 Virginia Manor Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	0
Buildings & Improvements	13,679
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	4,764
Total Costs
Land	0
Buildings & Improvements	18,443
Total	18,443	[1]
Accumulated Depreciation	(7,244)	[2]
Net Cost Basis	11,199
14225 Newbrook Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	28,659	[7]
Initial Costs
Land	4,800
Buildings & Improvements	27,639
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	5,354
Total Costs
Land	4,800
Buildings & Improvements	32,993
Total	37,793	[1]
Accumulated Depreciation	(11,756)	[2]
Net Cost Basis	26,037
1201/1208 Eastlake Avenue
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	42,366	[7]
Initial Costs
Land	5,810
Buildings & Improvements	47,149
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	14,955
Total Costs
Land	5,810
Buildings & Improvements	62,104
Total	67,914	[1]
Accumulated Depreciation	(17,337)	[2]
Net Cost Basis	50,577
1616 Eastlake Avenue
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	6,940
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	80,418
Total Costs
Land	6,940
Buildings & Improvements	80,418
Total	87,358	[1]
Accumulated Depreciation	(15,772)	[2]
Net Cost Basis	71,586
1551 Eastlake Avenue
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	7,292
Buildings & Improvements	17,161
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	33,267
Total Costs
Land	7,292
Buildings & Improvements	50,428
Total	57,720	[1]
Accumulated Depreciation	(4,867)	[2]
Net Cost Basis	52,853
199 East Blaine Street
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	240
Initial Costs
Land	6,528
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	71,679
Total Costs
Land	6,528
Buildings & Improvements	71,679
Total	78,207	[1]
Accumulated Depreciation	(7,916)	[2]
Net Cost Basis	70,291
219 Terry Avenue North
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,819
Buildings & Improvements	2,302
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	18,540
Total Costs
Land	1,819
Buildings & Improvements	20,842
Total	22,661	[1]
Accumulated Depreciation	(1,176)	[2]
Net Cost Basis	21,485
1600 Fairview Avenue
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	2,212
Buildings & Improvements	6,788
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	5,962
Total Costs
Land	2,212
Buildings & Improvements	12,750
Total	14,962	[1]
Accumulated Depreciation	(2,274)	[2]
Net Cost Basis	12,688
3000/3018 Western Avenue
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,432
Buildings & Improvements	7,497
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	15,159
Total Costs
Land	1,432
Buildings & Improvements	22,656
Total	24,088	[1]
Accumulated Depreciation	(6,918)	[2]
Net Cost Basis	17,170
410 West Harrison/410 Elliott Avenue West
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	3,857
Buildings & Improvements	1,989
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	10,477
Total Costs
Land	3,857
Buildings & Improvements	12,466
Total	16,323	[1]
Accumulated Depreciation	(2,250)	[2]
Net Cost Basis	14,073
Alexandria Technology Center Alston
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	913
Buildings & Improvements	17,482
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	25,221
Total Costs
Land	913
Buildings & Improvements	42,703
Total	43,616	[1]
Accumulated Depreciation	(16,669)	[2]
Net Cost Basis	26,947
108/110/112/114 Alexander Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	0
Buildings & Improvements	376
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	41,996
Total Costs
Land	0
Buildings & Improvements	42,372
Total	42,372	[1]
Accumulated Depreciation	(10,294)	[2]
Net Cost Basis	32,078
Alexandria Innovation Center - Research Triangle Park
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,065
Buildings & Improvements	21,218
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	24,407
Total Costs
Land	1,065
Buildings & Improvements	45,625
Total	46,690	[1]
Accumulated Depreciation	(9,919)	[2]
Net Cost Basis	36,771
6 Davis Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	821
Buildings & Improvements	10,712
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	500
Total Costs
Land	821
Buildings & Improvements	11,212
Total	12,033	[1]
Accumulated Depreciation	(644)	[2]
Net Cost Basis	11,389
7 Triangle Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	701
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	31,643
Total Costs
Land	701
Buildings & Improvements	31,643
Total	32,344	[1]
Accumulated Depreciation	(2,048)	[2]
Net Cost Basis	30,296
407 Davis Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,229
Buildings & Improvements	17,733
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	0
Total Costs
Land	1,229
Buildings & Improvements	17,733
Total	18,962	[1]
Accumulated Depreciation	(137)	[2]
Net Cost Basis	18,825
2525 East NC Highway 54
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	713
Buildings & Improvements	12,827
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	843
Total Costs
Land	713
Buildings & Improvements	13,670
Total	14,383	[1]
Accumulated Depreciation	(3,314)	[2]
Net Cost Basis	11,069
601 Keystone Park Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	785
Buildings & Improvements	11,546
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	4,989
Total Costs
Land	785
Buildings & Improvements	16,535
Total	17,320	[1]
Accumulated Depreciation	(2,713)	[2]
Net Cost Basis	14,607
5 Triangle Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	161
Buildings & Improvements	3,409
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	2,857
Total Costs
Land	161
Buildings & Improvements	6,266
Total	6,427	[1]
Accumulated Depreciation	(1,912)	[2]
Net Cost Basis	4,515
6101 Quadrangle Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	951
Buildings & Improvements	3,982
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	8,400
Total Costs
Land	951
Buildings & Improvements	12,382
Total	13,333	[1]
Accumulated Depreciation	(885)	[2]
Net Cost Basis	12,448
555 Heritage Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	2,919
Buildings & Improvements	5,311
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	11,937
Total Costs
Land	2,919
Buildings & Improvements	17,248
Total	20,167	[1]
Accumulated Depreciation	(2,023)	[2]
Net Cost Basis	18,144
1781 W. 75th Avenue
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	2,253
Buildings & Improvements	4,644
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	9,281
Total Costs
Land	2,253
Buildings & Improvements	13,925
Total	16,178	[1]
Accumulated Depreciation	(2,086)	[2]
Net Cost Basis	14,092
7990 Enterprise Street
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	2,491
Buildings & Improvements	9,589
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	109
Total Costs
Land	2,491
Buildings & Improvements	9,698
Total	12,189	[1]
Accumulated Depreciation	(1,922)	[2]
Net Cost Basis	10,267
275 Armand Frappier
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	7,643
Buildings & Improvements	23,043
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	8,983
Total Costs
Land	7,643
Buildings & Improvements	32,026
Total	39,669	[1]
Accumulated Depreciation	(5,140)	[2]
Net Cost Basis	34,529
525 Cartier Boulevard West
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	3,201
Buildings & Improvements	20,511
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	0
Total Costs
Land	3,201
Buildings & Improvements	20,511
Total	23,712	[1]
Accumulated Depreciation	(4,525)	[2]
Net Cost Basis	19,187
661 University Avenue (12)
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0	[11]
Initial Costs
Land	0	[11]
Buildings & Improvements	0	[11]
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	87,200	[11]
Total Costs
Land	0	[11]
Buildings & Improvements	87,200	[11]
Total	87,200	[1],[11]
Accumulated Depreciation	(9,302)	[11],[2]
Net Cost Basis	77,898	[11]
129/161/165 North Hill Avenue & 6 Thomas
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	3,091
Buildings & Improvements	5,546
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	15,325
Total Costs
Land	3,091
Buildings & Improvements	20,871
Total	23,962	[1]
Accumulated Depreciation	(5,769)	[2]
Net Cost Basis	18,193
China
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	0
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	58,831
Total Costs
Land	0
Buildings & Improvements	58,831
Total	58,831	[1]
Accumulated Depreciation	(1,709)	[2]
Net Cost Basis	57,122
India
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	742
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	47,526
Total Costs
Land	742
Buildings & Improvements	47,526
Total	48,268	[1]
Accumulated Depreciation	(3,015)	[2]
Net Cost Basis	45,253
Various
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	8,231
Buildings & Improvements	12,147
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	101,847
Total Costs
Land	8,231
Buildings & Improvements	113,994
Total	122,225	[1]
Accumulated Depreciation	(26,068)	[2]
Net Cost Basis	96,157
7330 Carroll Road, 100 Phillips Parkway, 79/96 Thirteen Street, Alexandria Park at 128
Total Costs
Secured notes payable	31,308
Number of real estate properties subject to secured debt	4
Alexandria at 128, 3165 Porter Drive, ARE Towne Center, 5810/5820/6138/6150 Nancy Ridge Drive
Total Costs
Secured notes payable	79,030
Number of real estate properties subject to secured debt	6
Alexandria Technology Center - Gateway, 7000 Shoreline Court
Total Costs
Secured notes payable	131,854
Number of real estate properties subject to secured debt	4
14225 Newbrook Drive, 1201 and 1208 Eastlake Avenue, 13112 Evening Creek Drive, ARE Esplanade, ARE Sunrise
Total Costs
Secured notes payable	$ 115,021
Number of real estate properties subject to secured debt	6
Land improvements
Total Costs
Estimated useful life	20 years
Minimum | Buildings and building improvements
Total Costs
Estimated useful life	30 years
Maximum | Buildings and building improvements
Total Costs
Estimated useful life	40 years
Asset under Construction | 661 University Avenue (12)
Total Costs
Gross investment per square foot	112
Term of operating lease obligation related to office leases	48 years
Area of real estate property	780,540

[1] The aggregate cost of real estate for federal income tax purposes is not materially different from the cost basis under GAAP (unaudited).

[2] The depreciable life for buildings and improvements ranges from 30 to 40 years, 20 for land improvements, and the term of the respective lease for tenant improvement.

[3] The balance shown includes an unamortized discount of $226.

[4] Loan of $31,308 secured by four properties identified by this reference.

[5] Loan of $79,030 secured by six properties identified by this reference.

[6] Loan of $131,854 secured by four properties identified by this reference.

[7] Loan of $115,021 secured by six properties identified by this reference.

[8] The balance shown includes an unamortized premium of $39.

[9] The balance shown includes an unamortized premium of $90.

[10] The balance shown includes an unamortized premium of $91.

[11] Represents land and land improvements with a gross investment of approximately $112 per RSF at December 31, 2013, which we have leased to a client tenant with a remaining lease term of approximately 48 years. Our client tenant has commenced construction of a 780,540 RSF multi-tenant laboratory/office building in Toronto. Pursuant to our lease, we are not required to contribute additional capital towards the project. In addition, we expect to receive rent under our lease upon stabilization of the project.