The Treasury Tunnel is the eastern end of the Idarado Mine, one of the larger mines in the San Juans, containing nearly 100 miles of underground tunnels. Miners entered here at the Treasury Tunnel and rode underground trams to their work stations. The western end of the mine complex is at Pandora, about 2 miles from Telluride. The Idarado Mine produced until the 1980s, and reclamation work is presently under way.