Quarterly report pursuant to Section 13 or 15(d)

Properties, Net

Properties, Net
9 Months Ended
Sep. 30, 2021
Real Estate [Abstract]  
Properties, Net Properties, Net
Operating properties, net consisted of the following (in thousands): 
September 30,
December 31, 2020
Land $ 539,899  $ 528,269 
Buildings and improvements 3,890,678  3,711,264 
Less: Accumulated depreciation (1,202,780) (1,124,253)
Operating properties, net $ 3,227,797  $ 3,115,280 

As of September 30, 2021, we had one property in our data center shells sub-segment previously removed from service that was classified as assets held for sale, net on our consolidated balance sheet, the sole component of which was properties, net.

2021 Dispositions

On June 2, 2021, we sold a 90% interest in two data center shell properties in Northern Virginia based on an aggregate property value of $118.8 million and retained a 10% interest in the properties through B RE COPT DC JV III LLC, a newly-formed joint venture. Our partner in the joint venture acquired the 90% interest from us for $106.9 million. We account for our interest in the joint venture using the equity method of accounting as described further in Note 6. We recognized a gain on sale of $40.2 million in the nine months ended September 30, 2021.

2021 Development Activities
During the nine months ended September 30, 2021, we placed into service 709,000 square feet in six newly-developed properties. As of September 30, 2021, we had 13 properties under development, including three partially-operational properties, that we estimate will total 1.8 million square feet upon completion.