Hangar One is one of the world's largest freestanding structures, covering 8 acres (3.2 ha) at Moffett Field near Mountain View, California in the San Francisco Bay Area. The massive hangar 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 hangar for the USS Macon and is now part of the NASA Ames Research Center.