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


	September 30,		December 31,
	2013		2012
Industrial operating properties (1):
Improved land	$	4,311,193	$	5,317,123
Buildings and improvements		14,093,704		17,291,125
Development portfolio, including cost of land (2)		1,084,959		951,643
Land (3)		1,643,055		1,794,364
Other real estate investments (4)		466,997		454,868

Total investments in real estate properties		21,599,908		25,809,123
Less accumulated depreciation		2,540,370		2,480,660

Net investments in properties	$	19,059,538	$	23,328,463

(1)

At September 30, 2013 and December 31, 2012, we had 1,650 and 1,853 industrial properties consisting of 268.5 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. At September 30, 2013, we had 30 properties aggregating 9.9 million square feet with an estimated value of $713.1 million that were acquired in connection with the wind down of Prologis Japan Fund 1 in June 2013 and the NAIF III acquisition in August 2013. See Notes 2 and 4 for further discussion on these transactions.

(2)

At September 30, 2013, the development portfolio consisted of 32 properties aggregating 15.1 million square feet under development with estimated completion dates primarily in 2013 and 2014 and 14 properties aggregating 6.3 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 10,217 acres and 10,915 acres at September 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) costs related to future development projects, including purchase options on land; (vi) restricted funds that are held in escrow pending the completion of tax-deferred exchange transactions involving operating properties; and (vii) earnest money deposits associated with potential acquisitions.