Hangar One, Moffett Air Field
Hangar One is one of the world's largest freestanding structures, covering 8 acres (3.2 ha), and has long been one of the most recognizable landmarks of California's Silicon Valley. An early example of mid-century modern architecture, it was built in the 1930s as a naval airship station for the USS Macon. (Wikipedia)
In 2003 it was discovered that the structure was leaking toxic chemicals into the nearby water systems. All the external cladding from the hangar was removed this year in an effort to remove the toxins from the site. The hangar will be left in its skeletal state until a decision is made on the future of this site.