K-25

K-25 is a center of uranium production and research that uses gaseous diffusion method belongs to the united states in rural Tennessee. This place is situated in Oak Ridge, Tennessee, at the southwestern tip of the Oak Ridge Reservation, USA.
The name "K-25" is a combination of "K" from Kellex Corporation, the initial contractor factory, and World War II-era code name for uranium-235.

Building area of ​​609,000 m² was built in June 1943 and completed in early 1945, with a cost up to 512 million dollars. And this building is one of the largest buildings in the world.