Property

Our property consists of the following (in thousands):



	June 30, 2018		December 31, 2017
Land	$	980,308	$	1,068,022
Land held for development	66,062		69,205
Land under development	49,670		48,985
Buildings and improvements	3,108,691		3,232,074
Construction in-progress	122,279		80,573
Total	$	4,327,010	$	4,498,859

During the six months ended June 30, 2018, we sold 14 centers and other property. Aggregate gross sales proceeds from these transactions approximated $334.1 million and generated gains of approximately $156.0 million, including properties previously classified as held for sale. Also, during the six months ended June 30, 2018, we invested $40.3 million in new development projects.

At June 30, 2018, two centers, totaling $35.5 million before accumulated depreciation, were classified as held for sale. At December 31, 2017, three centers, totaling $78.7 million before accumulated depreciation, were classified as held for sale. None of these centers qualified to be reported in discontinued operations.