California's largest and richest deep mine comprised 367mi of underground tunnels and produced 5.8 million troy ounces of gold during its century of operation (1856-1956). In the main shaft, visitors may stand on a platform located some 50ft below the surface for a gaze into the tunnel that extends more than 10,000ft to a depth of nearly a mile. Clustered about the mouth of the shaft is an assortment of equipment, processing buildings and administrative offices. The visitor center features a poignant photographic exhibit commemorating the hard life of the Cornish miners. Contained within the park are the handsome, redwood-paneled house and landscaped grounds of William Bourn Jr., owner of the mine from 1879 to 1929. There are also 8mi of hiking trails.