Schedule III - Real Estate and Accumulated Depreciation

12 Months Ended

Dec. 31, 2023

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract]

Schedule III-Real Estate and Accumulated Depreciation

				Initial Cost						Gross Amounts Carried At Close of Period
Property (Type) (1)	Location	Encumbrances (2)		Land		Building and Land Improvements		Costs Capitalized Subsequent to Acquisition		Land		Building and Land Improvements		Total (3)		Accumulated Depreciation (4)		Year Built or Renovated	Date Acquired (5)
100 Light Street (O)	Baltimore, MD	$	—	$	6,720	$	31,215	$	27,021	$	6,720	$	58,236	$	64,956	$	(36,309)	1973/2011	8/7/2015
100 Secured Gateway (O)	Huntsville, AL	—		—		71,174		52		—		71,226		71,226		(5,910)		2020	3/23/2010
1000 Redstone Gateway (O)	Huntsville, AL	8,461		—		20,533		217		—		20,750		20,750		(5,566)		2013	3/23/2010
1100 Redstone Gateway (O)	Huntsville, AL	9,163		—		19,593		2,929		—		22,522		22,522		(4,956)		2014	3/23/2010
114 National Business Parkway (O)	Annapolis Junction, MD	—		364		3,109		427		364		3,536		3,900		(1,883)		2002	6/30/2000
1200 Redstone Gateway (O)	Huntsville, AL	10,563		—		22,389		9,493		—		31,882		31,882		(6,195)		2013	3/23/2010
1201 M Street SE (O)	Washington, DC	—		—		49,775		10,883		—		60,658		60,658		(25,428)		2001	9/28/2010
1201 Winterson Road (O)	Linthicum, MD	—		2,130		17,207		937		2,130		18,144		20,274		(6,857)		1985/2017	4/30/1998
1220 12th Street SE (O)	Washington, DC	—		—		42,464		11,714		—		54,178		54,178		(23,306)		2003	9/28/2010
1243 Winterson Road (L)	Linthicum, MD	—		630		—		—		630		—		630		—		(6)	12/19/2001
131 National Business Parkway (O)	Annapolis Junction, MD	—		1,906		7,623		6,520		1,906		14,143		16,049		(9,286)		1990	9/28/1998
132 National Business Parkway (O)	Annapolis Junction, MD	—		2,917		12,259		4,995		2,917		17,254		20,171		(11,842)		2000	5/28/1999
133 National Business Parkway (O)	Annapolis Junction, MD	—		2,517		10,068		6,842		2,517		16,910		19,427		(11,967)		1997	9/28/1998
134 National Business Parkway (O)	Annapolis Junction, MD	—		3,684		7,517		5,973		3,684		13,490		17,174		(9,640)		1999	11/13/1998
1340 Ashton Road (O)	Hanover, MD	—		905		3,620		2,631		905		6,251		7,156		(3,861)		1989	4/28/1999
13450 Sunrise Valley Drive (O)	Herndon, VA	—		1,386		5,576		5,076		1,386		10,652		12,038		(7,417)		1998	7/25/2003
13454 Sunrise Valley Drive (O)	Herndon, VA	—		2,847		11,986		12,997		2,847		24,983		27,830		(14,469)		1998	7/25/2003
135 National Business Parkway (O)	Annapolis Junction, MD	—		2,484		9,750		7,296		2,484		17,046		19,530		(12,106)		1998	12/30/1998
1362 Mellon Road (O)	Hanover, MD	—		950		3,864		3,031		950		6,895		7,845		(1,898)		2006	2/10/2006
13857 McLearen Road (O)	Herndon, VA	—		3,507		30,177		5,911		3,507		36,088		39,595		(16,023)		2007	7/11/2012
140 National Business Parkway (O)	Annapolis Junction, MD	—		3,407		24,167		2,975		3,407		27,142		30,549		(13,110)		2003	12/31/2003
141 National Business Parkway (O)	Annapolis Junction, MD	—		2,398		9,538		4,844		2,398		14,382		16,780		(10,511)		1990	9/28/1998
14280 Park Meadow Drive (O)	Chantilly, VA	—		3,731		15,953		5,641		3,731		21,594		25,325		(12,342)		1999	9/29/2004
1460 Dorsey Road (L)	Hanover, MD	—		1,577		187		—		1,577		187		1,764		—		(6)	2/28/2006
14840 Conference Center Drive (O)	Chantilly, VA	—		1,572		8,175		5,833		1,572		14,008		15,580		(8,945)		2000	7/25/2003
14850 Conference Center Drive (O)	Chantilly, VA	—		1,615		8,358		7,740		1,615		16,098		17,713		(8,803)		2000	7/25/2003
14900 Conference Center Drive (O)	Chantilly, VA	—		3,436		14,402		10,459		3,436		24,861		28,297		(15,682)		1999	7/25/2003
1501 South Clinton Street (O)	Baltimore, MD	—		13,137		20,753		46,956		13,137		67,709		80,846		(38,074)		2006	10/27/2009
15049 Conference Center Drive (O)	Chantilly, VA	—		4,415		20,365		18,213		4,415		38,578		42,993		(24,412)		1997	8/14/2002
15059 Conference Center Drive (O)	Chantilly, VA	—		5,753		13,615		9,602		5,753		23,217		28,970		(12,086)		2000	8/14/2002
1550 West Nursery Road (O)	Linthicum, MD	—		14,071		16,930		—		14,071		16,930		31,001		(7,415)		2009	10/28/2009
1560 West Nursery Road (O)	Linthicum, MD	—		1,441		113		—		1,441		113		1,554		(27)		2014	10/28/2009
1610 West Nursery Road (O)	Linthicum, MD	—		259		246		—		259		246		505		(42)		2016	4/30/1998
1616 West Nursery Road (O)	Linthicum, MD	—		393		3,323		75		393		3,398		3,791		(539)		2017	4/30/1998
1622 West Nursery Road (O)	Linthicum, MD	—		393		2,542		—		393		2,542		2,935		(436)		2016	4/30/1998
16442 Commerce Drive (O)	Dahlgren, VA	—		613		2,582		1,142		613		3,724		4,337		(2,275)		2002	12/21/2004
16480 Commerce Drive (O)	Dahlgren, VA	—		1,856		7,425		2,878		1,856		10,303		12,159		(5,623)		2000	12/28/2004

			Initial Cost			Gross Amounts Carried At Close of Period
Property (Type) (1)	Location	Encumbrances (2)	Land	Building and Land Improvements	Costs Capitalized Subsequent to Acquisition	Land	Building and Land Improvements	Total (3)	Accumulated Depreciation (4)	Year Built or Renovated	Date Acquired (5)
16501 Commerce Drive (O)	Dahlgren, VA	—	522	2,090	1,251	522	3,341	3,863	(1,794)	2002	12/21/2004
16539 Commerce Drive (O)	Dahlgren, VA	—	688	2,860	2,345	688	5,205	5,893	(3,316)	1990	12/21/2004
16541 Commerce Drive (O)	Dahlgren, VA	—	773	3,094	2,715	773	5,809	6,582	(3,540)	1996	12/21/2004
16543 Commerce Drive (O)	Dahlgren, VA	—	436	1,742	907	436	2,649	3,085	(1,543)	2002	12/21/2004
1751 Pinnacle Drive (O)	McLean, VA	—	4,762	26,046	33,008	4,762	59,054	63,816	(48,466)	1989/1995	9/23/2004
1753 Pinnacle Drive (O)	McLean, VA	—	3,729	21,500	27,446	3,729	48,946	52,675	(33,423)	1976/2004	9/23/2004
206 Research Boulevard (O)	Aberdeen, MD	—	—	—	—	—	—	—	—	2012	9/14/2007
209 Research Boulevard (O)	Aberdeen, MD	—	134	1,711	842	134	2,553	2,687	(874)	2010	9/14/2007
210 Research Boulevard (O)	Aberdeen, MD	—	113	1,402	539	113	1,941	2,054	(710)	2010	9/14/2007
2100 L Street (O)	Washington, DC	—	41,935	71,067	—	41,935	71,067	113,002	(6,645)	2020	8/11/2015
2100 Rideout Road (O)	Huntsville, AL	—	—	7,336	3,256	—	10,592	10,592	(3,248)	2016	3/23/2010
22289 Exploration Drive (O)	Lexington Park, MD	—	1,422	5,719	2,379	1,422	8,098	9,520	(4,804)	2000	3/24/2004
22299 Exploration Drive (O)	Lexington Park, MD	—	1,278	5,791	3,085	1,278	8,876	10,154	(5,765)	1998	3/24/2004
22300 Exploration Drive (O)	Lexington Park, MD	—	1,094	5,038	3,060	1,094	8,098	9,192	(5,054)	1997	11/9/2004
22309 Exploration Drive (O)	Lexington Park, MD	—	2,160	10,419	8,179	2,160	18,598	20,758	(10,400)	1984/1997	3/24/2004
23535 Cottonwood Parkway (O)	California, MD	—	692	3,051	648	692	3,699	4,391	(2,524)	1984	3/24/2004
250 W Pratt St (O)	Baltimore, MD	—	4,704	21,487	21,784	4,704	43,271	47,975	(25,472)	1985	3/19/2015
2600 Park Tower Drive (O)	Vienna, VA	—	20,284	34,443	8,431	20,284	42,874	63,158	(11,121)	1999	4/15/2015
2691 Technology Drive (O)	Annapolis Junction, MD	—	2,098	17,334	9,191	2,098	26,525	28,623	(13,995)	2005	5/26/2000
2701 Technology Drive (O)	Annapolis Junction, MD	—	1,737	15,266	7,366	1,737	22,632	24,369	(14,744)	2001	5/26/2000
2711 Technology Drive (O)	Annapolis Junction, MD	—	2,251	21,611	4,509	2,251	26,120	28,371	(16,956)	2002	11/13/2000
2720 Technology Drive (O)	Annapolis Junction, MD	—	3,863	29,272	3,227	3,863	32,499	36,362	(16,331)	2004	1/31/2002
2721 Technology Drive (O)	Annapolis Junction, MD	—	4,611	14,597	3,836	4,611	18,433	23,044	(12,025)	2000	10/21/1999
2730 Hercules Road (O)	Annapolis Junction, MD	—	8,737	31,612	9,569	8,737	41,181	49,918	(26,409)	1990	9/28/1998
30 Light Street (O)	Baltimore, MD	—	—	2,501	625	—	3,126	3,126	(3,084)	2009	8/7/2015
300 Secured Gateway (O)	Huntsville, AL	—	—	63,500	—	—	63,500	63,500	(379)	2023	3/23/2010
300 Sentinel Drive (O)	Annapolis Junction, MD	—	1,517	59,165	2,590	1,517	61,755	63,272	(22,195)	2009	11/14/2003
302 Sentinel Drive (O)	Annapolis Junction, MD	—	2,648	29,687	6,540	2,648	36,227	38,875	(13,417)	2007	11/14/2003
304 Sentinel Drive (O)	Annapolis Junction, MD	—	3,411	24,917	5,335	3,411	30,252	33,663	(14,610)	2005	11/14/2003
306 Sentinel Drive (O)	Annapolis Junction, MD	—	3,260	22,592	3,755	3,260	26,347	29,607	(12,080)	2006	11/14/2003
308 Sentinel Drive (O)	Annapolis Junction, MD	—	1,422	26,208	2,365	1,422	28,573	29,995	(9,641)	2010	11/14/2003
310 Sentinel Way (O)	Annapolis Junction, MD	—	2,372	50,677	716	2,372	51,393	53,765	(8,291)	2016	11/14/2003
310 The Bridge Street (O)	Huntsville, AL	—	261	26,530	6,406	261	32,936	33,197	(14,449)	2009	8/9/2011
312 Sentinel Way (O)	Annapolis Junction, MD	—	3,138	27,797	—	3,138	27,797	30,935	(6,474)	2014	11/14/2003
314 Sentinel Way (O)	Annapolis Junction, MD	—	1,254	7,741	—	1,254	7,741	8,995	(1,947)	2008	11/14/2003
316 Sentinel Way (O)	Annapolis Junction, MD	—	2,748	38,156	298	2,748	38,454	41,202	(11,361)	2011	11/14/2003
318 Sentinel Way (O)	Annapolis Junction, MD	—	2,185	28,426	562	2,185	28,988	31,173	(13,016)	2005	11/14/2003

			Initial Cost			Gross Amounts Carried At Close of Period
Property (Type) (1)	Location	Encumbrances (2)	Land	Building and Land Improvements	Costs Capitalized Subsequent to Acquisition	Land	Building and Land Improvements	Total (3)	Accumulated Depreciation (4)	Year Built or Renovated	Date Acquired (5)
320 Sentinel Way (O)	Annapolis Junction, MD	—	2,067	21,623	148	2,067	21,771	23,838	(8,753)	2007	11/14/2003
322 Sentinel Way (O)	Annapolis Junction, MD	—	2,605	22,827	1,900	2,605	24,727	27,332	(10,851)	2006	11/14/2003
324 Sentinel Way (O)	Annapolis Junction, MD	—	1,656	23,018	61	1,656	23,079	24,735	(7,690)	2010	6/29/2006
4000 Market Street (O)	Huntsville, AL	5,914	—	9,198	1,955	—	11,153	11,153	(1,231)	2018	3/23/2010
410 National Business Parkway (O)	Annapolis Junction, MD	—	1,831	23,257	2,259	1,831	25,516	27,347	(8,066)	2012	6/29/2006
4100 Market Street (O)	Huntsville, AL	5,148	—	8,046	7	—	8,053	8,053	(913)	2019	3/23/2010
420 National Business Parkway (O)	Annapolis Junction, MD	—	2,370	31,397	3,199	2,370	34,596	36,966	(7,049)	2013	6/29/2006
430 National Business Parkway (O)	Annapolis Junction, MD	—	1,852	21,563	3,118	1,852	24,681	26,533	(7,560)	2011	6/29/2006
44408 Pecan Court (O)	California, MD	—	817	1,583	1,861	817	3,444	4,261	(2,432)	1986	3/24/2004
44414 Pecan Court (O)	California, MD	—	405	1,619	1,229	405	2,848	3,253	(2,015)	1986	3/24/2004
44417 Pecan Court (O)	California, MD	—	434	3,822	295	434	4,117	4,551	(2,576)	1989/2015	3/24/2004
44420 Pecan Court (O)	California, MD	—	344	890	329	344	1,219	1,563	(729)	1989	11/9/2004
44425 Pecan Court (O)	California, MD	—	1,309	3,506	2,694	1,309	6,200	7,509	(4,310)	1997	5/5/2004
45310 Abell House Lane (O)	California, MD	—	2,272	13,808	1,812	2,272	15,620	17,892	(5,025)	2011	8/30/2010
4600 River Road (O)	College Park, MD	—	—	26,255	—	—	26,255	26,255	(1,706)	2020	1/29/2008
46579 Expedition Drive (O)	Lexington Park, MD	—	1,406	5,796	2,987	1,406	8,783	10,189	(5,214)	2002	3/24/2004
46591 Expedition Drive (O)	Lexington Park, MD	—	1,200	7,199	4,727	1,200	11,926	13,126	(5,899)	2005	3/24/2004
4851 Stonecroft Boulevard (O)	Chantilly, VA	—	1,878	11,558	483	1,878	12,041	13,919	(5,618)	2004	8/14/2002
5300 Redstone Gateway (O)	Huntsville, AL	—	—	17,350	—	—	17,350	17,350	—	(7)	3/23/2010
540 National Business Parkway (O)	Annapolis Junction, MD	—	2,035	35,545	41	2,035	35,586	37,621	(5,003)	2017	6/29/2006
550 National Business Parkway (O)	Annapolis Junction, MD	—	2,678	43,521	—	2,678	43,521	46,199	(98)	2023	6/29/2006
5520 Research Park Drive (O)	Catonsville, MD	—	—	20,072	2,356	—	22,428	22,428	(8,416)	2009	4/4/2006
5522 Research Park Drive (O)	Catonsville, MD	—	—	4,550	883	—	5,433	5,433	(2,249)	2007	3/8/2006
560 National Business Parkway (O)	Annapolis Junction, MD	—	2,193	55,079	—	2,193	55,079	57,272	(1,635)	2022	6/29/2006
5801 University Research Court (O)	College Park, MD	10,640	—	17,431	162	—	17,593	17,593	(2,726)	2018	1/29/2008
5825 University Research Court (O)	College Park, MD	18,580	—	22,771	2,874	—	25,645	25,645	(9,925)	2008	1/29/2008
5850 University Research Court (O)	College Park, MD	19,657	—	31,906	1,112	—	33,018	33,018	(11,519)	2008	1/29/2008
6000 Redstone Gateway (O)	Huntsville, AL	—	—	8,542	17	—	8,559	8,559	(633)	2020	3/23/2010
610 Guardian Way (O)	Annapolis Junction, MD	—	7,636	53,682	—	7,636	53,682	61,318	(2,915)	2021	6/29/2006
6200 Redstone Gateway (O)	Huntsville, AL	—	—	50,086	—	—	50,086	50,086	(922)	2022	3/23/2010
6700 Alexander Bell Drive (O)	Columbia, MD	—	1,755	7,019	10,647	1,755	17,666	19,421	(11,013)	1988	5/14/2001
6708 Alexander Bell Drive (O)	Columbia, MD	—	897	12,693	1,618	897	14,311	15,208	(5,520)	1988/2016	5/14/2001
6711 Columbia Gateway Drive (O)	Columbia, MD	—	2,683	23,239	3,243	2,683	26,482	29,165	(11,617)	2006-2007	9/28/2000
6716 Alexander Bell Drive (O)	Columbia, MD	—	1,242	4,969	7,391	1,242	12,360	13,602	(7,078)	1990	12/31/1998
6721 Columbia Gateway Drive (O)	Columbia, MD	—	1,753	34,090	9,251	1,753	43,341	45,094	(15,125)	2009	9/28/2000
6724 Alexander Bell Drive (O)	Columbia, MD	—	449	5,039	2,680	449	7,719	8,168	(4,620)	2001	5/14/2001
6731 Columbia Gateway Drive (O)	Columbia, MD	—	2,807	19,098	6,920	2,807	26,018	28,825	(15,938)	2002	3/29/2000

			Initial Cost			Gross Amounts Carried At Close of Period
Property (Type) (1)	Location	Encumbrances (2)	Land	Building and Land Improvements	Costs Capitalized Subsequent to Acquisition	Land	Building and Land Improvements	Total (3)	Accumulated Depreciation (4)	Year Built or Renovated	Date Acquired (5)
6740 Alexander Bell Drive (O)	Columbia, MD	—	1,424	4,209	9,685	1,424	13,894	15,318	(3,397)	1992	12/31/1998
6741 Columbia Gateway Drive (O)	Columbia, MD	—	675	1,711	179	675	1,890	2,565	(807)	2008	9/28/2000
6750 Alexander Bell Drive (O)	Columbia, MD	—	1,263	12,461	6,070	1,263	18,531	19,794	(12,322)	2001	12/31/1998
6760 Alexander Bell Drive (O)	Columbia, MD	—	890	3,561	3,946	890	7,507	8,397	(5,576)	1991	12/31/1998
6940 Columbia Gateway Drive (O)	Columbia, MD	—	3,545	9,916	12,806	3,545	22,722	26,267	(13,989)	1999	11/13/1998
6950 Columbia Gateway Drive (O)	Columbia, MD	—	3,596	28,278	3,223	3,596	31,501	35,097	(14,171)	1998/2019	10/22/1998
7000 Columbia Gateway Drive (O)	Columbia, MD	—	3,131	12,103	10,509	3,131	22,612	25,743	(13,223)	1999	5/31/2002
7000 Redstone Gateway (O)	Huntsville, AL	—	—	8,900	—	—	8,900	8,900	(147)	2022	3/23/2010
7005 Columbia Gateway Drive (L)	Columbia, MD	—	3,036	747	—	3,036	747	3,783	—	(6)	6/26/2014
7015 Albert Einstein Drive (O)	Columbia, MD	—	2,058	6,093	3,560	2,058	9,653	11,711	(5,853)	1999	12/1/2005
7061 Columbia Gateway Drive (O)	Columbia, MD	—	729	3,094	2,907	729	6,001	6,730	(3,964)	2000	8/30/2001
7063 Columbia Gateway Drive (O)	Columbia, MD	—	902	3,684	3,707	902	7,391	8,293	(5,139)	2000	8/30/2001
7065 Columbia Gateway Drive (O)	Columbia, MD	—	919	3,763	3,302	919	7,065	7,984	(4,991)	2000	8/30/2001
7067 Columbia Gateway Drive (O)	Columbia, MD	—	1,829	11,823	9,177	1,829	21,000	22,829	(11,144)	2001	8/30/2001
7100 Redstone Gateway (O)	Huntsville, AL	—	—	12,989	—	—	12,989	12,989	(839)	2021	3/23/2010
7125 Columbia Gateway Drive (O)	Columbia, MD	—	20,487	49,926	29,466	20,487	79,392	99,879	(35,289)	1973/1999	6/29/2006
7130 Columbia Gateway Drive (O)	Columbia, MD	—	1,350	4,359	3,167	1,350	7,526	8,876	(4,626)	1989	9/19/2005
7134 Columbia Gateway Drive (O)	Columbia, MD	—	704	4,700	817	704	5,517	6,221	(2,330)	1990/2016	9/19/2005
7138 Columbia Gateway Drive (O)	Columbia, MD	—	1,104	3,518	2,989	1,104	6,507	7,611	(4,725)	1990	9/19/2005
7142 Columbia Gateway Drive (O)	Columbia, MD	—	1,342	7,148	4,265	1,342	11,413	12,755	(5,145)	1994/2018	9/19/2005
7150 Columbia Gateway Drive (O)	Columbia, MD	—	1,032	3,429	1,659	1,032	5,088	6,120	(2,392)	1991	9/19/2005
7150 Riverwood Drive (O)	Columbia, MD	—	1,821	4,388	16,234	1,821	20,622	22,443	(3,599)	2000	1/10/2007
7160 Riverwood Drive (O)	Columbia, MD	—	2,732	7,006	4,609	2,732	11,615	14,347	(6,322)	2000	1/10/2007
7170 Riverwood Drive (O)	Columbia, MD	—	1,283	3,096	2,389	1,283	5,485	6,768	(3,181)	2000	1/10/2007
7175 Riverwood Drive (O)	Columbia, MD	—	1,788	7,269	—	1,788	7,269	9,057	(1,842)	1996/2013	7/27/2005
7200 Redstone Gateway (O)	Huntsville, AL	—	—	8,348	185	—	8,533	8,533	(2,048)	2013	3/23/2010
7200 Riverwood Drive (O)	Columbia, MD	—	4,089	22,630	5,332	4,089	27,962	32,051	(15,053)	1986	10/13/1998
7205 Riverwood Drive (O)	Columbia, MD	—	1,367	21,419	—	1,367	21,419	22,786	(5,593)	2013	7/27/2005
7272 Park Circle Drive (O)	Hanover, MD	—	1,479	6,300	4,618	1,479	10,918	12,397	(6,956)	1991/1996	1/10/2007
7318 Parkway Drive (O)	Hanover, MD	—	972	3,888	2,297	972	6,185	7,157	(3,590)	1984	4/16/1999
7400 Redstone Gateway (O)	Huntsville, AL	—	—	9,223	75	—	9,298	9,298	(1,993)	2015	3/23/2010
7467 Ridge Road (O)	Hanover, MD	—	1,565	3,116	7,657	1,565	10,773	12,338	(5,750)	1990	4/28/1999
7500 Advanced Gateway (O)	Huntsville, AL	—	—	18,665	—	—	18,665	18,665	(1,667)	2020	3/23/2010
7600 Advanced Gateway (O)	Huntsville, AL	—	—	13,752	—	—	13,752	13,752	(1,170)	2020	3/23/2010
7740 Milestone Parkway (O)	Hanover, MD	—	3,825	34,176	1,855	3,825	36,031	39,856	(12,142)	2009	7/2/2007
7770 Backlick Road (O)	Springfield, VA	—	6,387	78,892	1,747	6,387	80,639	87,026	(21,899)	2012	3/10/2010
7880 Milestone Parkway (O)	Hanover, MD	—	4,857	27,173	1,619	4,857	28,792	33,649	(6,037)	2015	9/17/2013

			Initial Cost			Gross Amounts Carried At Close of Period
Property (Type) (1)	Location	Encumbrances (2)	Land	Building and Land Improvements	Costs Capitalized Subsequent to Acquisition	Land	Building and Land Improvements	Total (3)	Accumulated Depreciation (4)	Year Built or Renovated	Date Acquired (5)
8000 Rideout Road (O)	Huntsville, AL	—	—	28,155	49	—	28,204	28,204	(1,240)	2021	3/23/2010
8100 Rideout Road (O)	Huntsville, AL	—	—	29,681	—	—	29,681	29,681	—	(7)	3/23/2010
8200 Rideout Road (O)	Huntsville, AL	—	—	45,653	—	—	45,653	45,653	(1,556)	2022	3/23/2010
8300 Rideout Road (O)	Huntsville, AL	—	—	52,678	—	—	52,678	52,678	(1,803)	2022	3/23/2010
8600 Advanced Gateway (O)	Huntsville, AL	—	—	27,312	24	—	27,336	27,336	(2,079)	2020	3/23/2010
8621 Robert Fulton Drive (O)	Columbia, MD	—	2,317	12,642	8,084	2,317	20,726	23,043	(10,265)	2005-2006	6/10/2005
8661 Robert Fulton Drive (O)	Columbia, MD	—	1,510	3,764	3,379	1,510	7,143	8,653	(4,437)	2002	12/30/2003
8671 Robert Fulton Drive (O)	Columbia, MD	—	1,718	4,280	4,848	1,718	9,128	10,846	(5,796)	2002	12/30/2003
870 Elkridge Landing Road (O)	Linthicum, MD	—	2,003	9,442	10,464	2,003	19,906	21,909	(14,016)	1981	8/3/2001
8800 Redstone Gateway (O)	Huntsville, AL	11,413	—	18,470	—	—	18,470	18,470	(1,900)	2019	3/23/2010
891 Elkridge Landing Road (O)	Linthicum, MD	—	1,165	4,772	4,192	1,165	8,964	10,129	(6,042)	1984	7/2/2001
901 Elkridge Landing Road (O)	Linthicum, MD	—	1,156	4,437	7,429	1,156	11,866	13,022	(6,397)	1984	7/2/2001
911 Elkridge Landing Road (O)	Linthicum, MD	—	1,215	4,861	3,383	1,215	8,244	9,459	(5,783)	1985	4/30/1998
938 Elkridge Landing Road (O)	Linthicum, MD	—	922	4,748	1,538	922	6,286	7,208	(3,816)	1984	7/2/2001
939 Elkridge Landing Road (O)	Linthicum, MD	—	939	3,756	6,229	939	9,985	10,924	(6,565)	1983	4/30/1998
Arundel Preserve (L)	Hanover, MD	—	13,352	9,888	—	13,352	9,888	23,240	—	(6)	7/2/2007
Canton Crossing Land (L)	Baltimore, MD	—	—	6,009	57	—	6,066	6,066	(57)	(6)	10/27/2009
Canton Crossing Util Distr Ctr (O)	Baltimore, MD	—	2,866	7,271	1,976	2,866	9,247	12,113	(8,026)	2006	10/27/2009
Columbia Gateway - Southridge (L)	Columbia, MD	—	6,387	3,725	—	6,387	3,725	10,112	—	(6)	9/20/2004
Dahlgren Technology Center (L)	Dahlgren, VA	—	978	178	—	978	178	1,156	—	(6)	3/16/2005
Expedition VII (O)	Lexington Park, MD	—	705	8,366	—	705	8,366	9,071	(319)	2022	3/24/2004
M Square Research Park (L)	College Park, MD	—	—	3,352	—	—	3,352	3,352	—	(6)	1/29/2008
MP 3 (O)	Northern Virginia	—	9,038	993	—	9,038	993	10,031	—	(7)	11/8/2018
National Business Park North (L)	Annapolis Junction, MD	—	15,554	28,744	—	15,554	28,744	44,298	—	(6)	6/29/2006
North Gate Business Park (L)	Aberdeen, MD	—	1,755	5	—	1,755	5	1,760	—	(6)	9/14/2007
NoVA Office A (O)	Chantilly, VA	—	2,096	46,849	—	2,096	46,849	48,945	(10,436)	2015	7/18/2002
NoVA Office B (O)	Chantilly, VA	—	739	38,376	—	739	38,376	39,115	(6,675)	2016	7/18/2002
NoVA Office C (O)	Chantilly, VA	—	7,751	84,815	—	7,751	84,815	92,566	(4,503)	2021	7/18/2002
NoVA Office D (O)	Chantilly, VA	—	6,587	40,559	—	6,587	40,559	47,146	(6,499)	2017	7/2/2013
Oak Grove A (O)	Northern Virginia	—	12,866	42,087	—	12,866	42,087	54,953	(3,279)	2020	11/1/2018
Oak Grove B (O)	Northern Virginia	—	12,866	41,621	—	12,866	41,621	54,487	(3,908)	2019	11/1/2018
Oak Grove C (O)	Northern Virginia	—	11,741	78,829	—	11,741	78,829	90,570	(3,323)	2022	11/1/2018
Oak Grove D (O)	Northern Virginia	—	11,741	77,097	—	11,741	77,097	88,838	(2,096)	2022	11/1/2018
Old Annapolis Road (O)	Columbia, MD	—	1,637	5,500	6,985	1,637	12,485	14,122	(6,432)	1974/1985	12/14/2000
Patriot Ridge (L)	Springfield, VA	—	18,517	14,616	—	18,517	14,616	33,133	—	(6)	3/10/2010
Project EL (O)	Confidential-USA	—	7,190	46,912	—	7,190	46,912	54,102	(2,878)	2021	1/20/2006
Project EX (O)	Confidential-USA	—	13,010	19,107	—	13,010	19,107	32,117	(2,225)	2018	7/16/2008

				Initial Cost						Gross Amounts Carried At Close of Period
Property (Type) (1)	Location	Encumbrances (2)		Land		Building and Land Improvements		Costs Capitalized Subsequent to Acquisition		Land		Building and Land Improvements		Total (3)		Accumulated Depreciation (4)		Year Built or Renovated	Date Acquired (5)
PS A (O)	Northern Virginia	—		4,078		54,122		—		4,078		54,122		58,200		(512)		2023	1/27/2005
PS B (O)	Northern Virginia	—		3,468		45,377		—		3,468		45,377		48,845		(82)		2023	1/27/2005
Redstone Gateway (L)	Huntsville, AL	—		—		31,193		—		—		31,193		31,193		—		(6)	3/23/2010
Sentry Gateway - T (O)	San Antonio, TX	—		14,020		38,804		13		14,020		38,817		52,837		(16,384)		1982/2008	3/30/2005
Sentry Gateway - V (O)	San Antonio, TX	—		—		1,066		—		—		1,066		1,066		(401)		2007	3/30/2005
Sentry Gateway - W (O)	San Antonio, TX	—		—		1,884		71		—		1,955		1,955		(703)		2009	3/30/2005
Sentry Gateway - X (O)	San Antonio, TX	—		1,964		21,178		53		1,964		21,231		23,195		(6,978)		2010	1/20/2006
Sentry Gateway - Y (O)	San Antonio, TX	—		1,964		21,298		8		1,964		21,306		23,270		(7,007)		2010	1/20/2006
Sentry Gateway - Z (O)	San Antonio, TX	—		1,964		30,573		—		1,964		30,573		32,537		(6,733)		2015	6/14/2005
Southpoint Phase 2 Bldg A (O)	Northern Virginia	—		4,404		16,356		—		4,404		16,356		20,760		—		(7)	7/24/2019
Southpoint Phase 2 Bldg B (O)	Northern Virginia	—		3,752		1,398		—		3,752		1,398		5,150		—		(7)	7/24/2019
Westfields - Park Center (L)	Chantilly, VA	—		8,667		3,515		—		8,667		3,515		12,182		—		(6)	7/2/2013
Other Developments, including    intercompany eliminations (V)	Various	—		—		1,140		258		—		1,398		1,398		(167)		Various	Various
		$	99,539	$	570,610	$	3,607,812	$	725,418	$	570,610	$	4,333,230	$	4,903,840	$	(1,400,162)

(1)A legend for the Property Type follows: (O) = Office or data center shell property; (L) = Land held or pre-development; and (V) = Various.

(2)Excludes our Revolving Credit Facility of $75.0 million, term loan facilities of $124.3 million, unsecured senior notes of $2.1 billion, unsecured notes payable of $430,000, and deferred financing costs, net of premiums, on the remaining loans of $331,000.

(3)The aggregate cost of these assets for federal income tax purposes was approximately $3.8 billion as of December 31, 2023.

(4)The estimated lives over which depreciation is recognized follow: Building and land improvements: 10-40 years; and tenant improvements: related lease terms.

(5)The acquisition date of multi-parcel properties reflects the date of the earliest parcel acquisition. The acquisition date of properties owned through real estate joint ventures reflects the date of the formation of the joint venture.

(6)Held as of December 31, 2023.

(7)Under development as of December 31, 2023.

The following table summarizes our changes in cost of properties for the years ended December 31, 2023, 2022 and 2021 (in thousands):

	2023		2022		2021
Beginning balance	$	4,986,537	$	4,959,709	$	4,686,802
Improvements and other additions	333,081		350,702		342,684
Sales (1)	(162,981)		(323,874)		(103,097)
Impairments (2)	(252,797)		—		—
Other dispositions	—		—		(4,511)
Reclassification from right-of-use asset	—		—		37,831
Ending balance	$	4,903,840	$	4,986,537	$	4,959,709
The following table summarizes our changes in accumulated depreciation for the same time periods (in thousands):
	2023		2022		2021
Beginning balance	$	1,273,448	$	1,234,908	$	1,124,253
Depreciation expense	132,728		124,803		130,604
Sales (1)	(6,014)		(86,263)		(15,438)
Other dispositions	—		—		(4,511)
Ending balance	$	1,400,162	$	1,273,448	$	1,234,908

(1)Includes sales of our wholesale data center and ownership interests in data center shells through newly-formed unconsolidated real estate joint ventures, as described in Note 4 to our consolidated financial statements.

(2)Includes impairment recognized on six operating properties and a parcel of land, as described in Note 4 to our consolidated financial statements.