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INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Mortgage Maturities) (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	May 31, 2018	Oct. 13, 2016
Annual maturities of mortgage debt
2021-current maturities	$ 2,743,000
2022	102,672,000
2023	10,935,000
2024	3,260,000
2025	24,870,000
Thereafter	138,605,000
Total	283,085,000
Less: unamortized deferred financing costs	(1,165,000)
Secured Debt	$ 281,919,669	$ 283,444,533
Weighted average interest rate (as a percent)	3.91%
Effective interest rate (as a percent)	3.97%
Investment Properties
Annual maturities of mortgage debt
2021-current maturities	$ 219,910
2022	228,573
2023	17,137,577
2024	10,246,936
2025	256,664
Thereafter	138,800,134
Total	166,889,794
Less: unamortized deferred financing costs	(659,231)
Secured Debt	166,230,563		$ 166,332,832
Hamilton Essex 81
Annual maturities of mortgage debt
2024	10,000,000
Total	10,000,000
Less: unamortized deferred financing costs	(55,156)
Secured Debt	9,944,844		9,931,055
345 Franklin
Annual maturities of mortgage debt
2021-current maturities	219,910
2022	228,573
2023	237,577
2024	246,936
2025	256,664
Thereafter	7,800,134
Total	8,989,794
Less: unamortized deferred financing costs	(44,945)
Secured Debt	8,944,849		9,149,766
Hamilton Minuteman
Annual maturities of mortgage debt
Thereafter	6,000,000
Total	6,000,000
Less: unamortized deferred financing costs	(81,494)				$ (123,000)
Secured Debt	5,918,506		5,910,322
Hamilton on Main Apts
Annual maturities of mortgage debt
2023	16,900,000
Total	16,900,000
Less: unamortized deferred financing costs	(46,816)
Secured Debt	16,853,184		16,837,132
Dexter Park
Annual maturities of mortgage debt
Thereafter	125,000,000
Total	125,000,000
Less: unamortized deferred financing costs	(430,820)
Secured Debt	$ 124,569,180		$ 124,504,557	$ 82,000,000