One of the two World War II-era blimp hangars on the former Marine Corps Air Station in Tustin, California. I posted another angle on this one a few years back.
The base was decommissioned in the 1990s, and last I heard, the fate of these historic buildings is still up in the air. The trick is finding the means to preserve them.
View on Flickr: Blimp Hangar Looming.