United States Mint

The Government Mint is located in Washington, D.C.

Earth-2A
It was where the Gold Transport Train transported a billion dollars worth a gold to.

Earth-1A
The Government Mint also had a branch in the city of Metropolis called the Metropolis Mint.

Appearances/References
Superman (1940s cartoons) The New Adventures of Superman
 * Billion Dollar Limited
 * Merlin's Magic Marbles