PROPERTY AND EQUIPMENT

Property and equipment, at cost, consisted of the following (in millions):



	December 31,
	2017		2018
Gross property and equipment (1):
Land and buildings	$	23,896	$	31,741
Equipment	42,244		54,591
Other assets	2,438		2,577
Construction in progress	4,078		6,861
Gross property and equipment	72,656		95,770
Total accumulated depreciation and amortization (1)	23,790		33,973
Total property and equipment, net	$	48,866	$	61,797

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(1)	We revised our prior year presentation of gross property and equipment and total accumulated depreciation and amortization to include all property and equipment in service, including equipment which is fully-depreciated, to conform to the current year presentation. Total property and equipment, net remains unchanged for the prior year.

Depreciation expense on property and equipment was $6.4 billion, $8.8 billion, and $12.1 billion which includes amortization of property and equipment acquired under capital leases of $3.8 billion, $5.4 billion, and $7.3 billion for 2016, 2017, and 2018. Gross assets recorded under capital leases were $26.4 billion and $36.1 billion as of December 31, 2017 and 2018. Accumulated amortization associated with capital leases was $13.4 billion and $19.8 billion as of December 31, 2017 and 2018.

We capitalize construction in progress and record a corresponding long-term liability for build-to-suit lease agreements where we are considered the owner, for accounting purposes, during the construction period. For buildings under build-to-suit lease arrangements where we have taken occupancy, which do not qualify for sales recognition under the sale-leaseback accounting guidance, we determined that we continue to be the deemed owner of these buildings. This is principally due to our significant investment in tenant improvements. As a result, the buildings are being depreciated over the shorter of their useful lives or the related leases’ terms. Additionally, certain build-to-suit lease arrangements and finance leases provide purchase options. Upon occupancy, the long-term construction obligations are considered long-term finance lease obligations with amounts payable during the next 12 months recorded as “Accrued expenses and other.” Gross assets remaining under finance leases were $5.4 billion and $7.5 billion as of December 31, 2017 and 2018. Accumulated amortization associated with finance leases was $635 million and $1.1 billion as of December 31, 2017 and 2018. As disclosed in “Note 1 — Description of Business and Accounting Policies,” our accounting for build-to-suit and finance leases will change on January 1, 2019.