NOTE 2. REAL ESTATE

Investments in real estate properties consisted of the following (dollars and square feet in thousands):

	Square Feet				Number of Buildings
	March 31,		December 31,		March 31,		December 31,		March 31,		December 31,
	2018		2017		2018		2017		2018		2017
Operating properties:
Buildings and improvements		290,474		294,811		1,511		1,525	$	16,720,688	$	16,849,349
Improved land										5,700,945		5,735,978
Development portfolio, including land costs:
Prestabilized		6,512		7,345		22		22		501,772		546,173
Properties under development		23,116		22,216		62		63		1,195,715		1,047,316
Land (1)										1,231,759		1,154,383
Other real estate investments (2)										525,123		505,445
Total investments in real estate properties										25,876,002		25,838,644
Less accumulated depreciation										4,199,159		4,059,348
Net investments in real estate properties									$	21,676,843	$	21,779,296

(1)	Included in our investments in real estate at March 31, 2018 and December 31, 2017, were 5,224 and 5,191 acres of land, respectively. During the three months ended March 31, 2018, we acquired 379 acres of land for $134.9 million.

(2)

Included in other real estate investments were: (i) non-logistics real estate; (ii) land parcels that are ground leased to third parties; (iii) our corporate office buildings; (iv) costs related to future development projects, including purchase options on land; (v) infrastructure costs related to projects we are developing on behalf of others; and (vi) earnest money deposits associated with potential acquisitions.

Dispositions

The following table summarizes our real estate disposition activity (dollars and square feet in thousands):

	Three Months Ended March 31,
	2018		2017
Contributions to unconsolidated co-investment ventures
Number of properties		8		5
Square feet		3,078		2,769
Net proceeds (1)	$	539,822	$	397,489
Gains on contributions, net (1) (2)	$	167,726	$	88,366
Dispositions to third parties
Number of properties		11		18
Square feet		1,303		2,318
Net proceeds (1) (3)	$	87,981	$	243,389
Gains on dispositions, net (1) (3)	$	27,385	$	8,959

Total gains on dispositions of investments in real estate, net	$	195,111	$	97,325

(1)	Includes the contribution and disposition of land parcels.

(2)

The three months ended March 31, 2018 reflects the adoption of the new revenue recognition standard under which we recognized the entire gain attributed to contributions of real estate properties to unconsolidated entities. The three months ended March 31, 2017 reflects our prior recognition of the gain to the extent of the third-party ownership in the unconsolidated entity acquiring the property with the deferral of a portion of the gain related to our ownership.

(3)	Includes the sale of our investment in Europe Logistics Venture 1 in January 2017.