Investments in real estate properties are presented at cost, and consisted of the following (in thousands):


	June 30,		December 31,
	2013		2012
Industrial operating properties (1):
Improved land	$	4,141,908	$	5,317,123
Buildings and improvements		13,613,747		17,291,125
Development portfolio, including cost of land (2)		939,794		951,643
Land (3)		1,710,583		1,794,364
Other real estate investments (4)		492,833		454,868

Total investments in real estate properties		20,898,865		25,809,123
Less accumulated depreciation		2,422,909		2,480,660

Net investments in properties	$	18,475,956	$	23,328,463

(1)

At June 30, 2013 and December 31, 2012, we had 1,652 and 1,853 industrial properties consisting of 263.0 million square feet and 316.3 million square feet, respectively. In 2013, in connection with our two new ventures in Japan and Europe, we contributed 207 properties with a net carrying value of $4.6 billion, consisting of 58.3 million square feet for gross proceeds of $4.9 billion. In connection with the wind down of Japan Fund 1 in June 2013, we purchased 14 properties aggregating 1.8 million square feet with an estimated value of $212.5 million from the venture. See Note 4 for further discussion on these transactions.

(2)

At June 30, 2013, the development portfolio consisted of 31 properties aggregating 15.3 million square feet under development with estimated completion dates primarily in 2013 and 2014 and 12 properties aggregating 2.8 million square feet of pre-stabilized completed properties. At December 31, 2012, the development portfolio consisted of 30 properties aggregating 13.2 million square feet that were under development and 15 properties aggregating 4.8 million square feet that were pre-stabilized completed properties.

(3)	Land consisted of 10,392 acres and 10,915 acres at June 30, 2013 and December 31, 2012, respectively, and included land parcels that we may develop or sell depending on market conditions and other factors.

(4)

Included in other investments were: (i) certain non-industrial real estate; (ii) our corporate office buildings; (iii) land parcels that are ground leased to third parties; (iv) certain infrastructure costs related to projects we are developing on behalf of others; (v) earnest money deposits associated with potential acquisitions; (vi) restricted funds that are held in escrow pending the completion of tax-deferred exchange transactions involving operating properties; and (vii) costs related to future development projects, including purchase options on land.