Empire Mine State Historic Park is the site of one of the oldest, largest, deepest, longest and richest gold mines in California. The park is in Grass Valley at 10791 East Empire Street. In existence for more than 100 years, the mine produced 5.6 million ounces of gold before it closed in 1956. (5.6 million ounces of gold is equivalent to a box seven feet long, seven feet high, and seven feet deep filled with gold.) The park contains many of the mine?s buildings, the owner?s home and restored gardens, as well as the entrance to 367 miles (the distance, as the crow flies, from Grass Valley to Magic Mountain) of abandoned and flooded mine shafts. The park consists of forested backcountry and eight miles of trails ? including easy hikes (for hiking, mountain biking and horseback riding) - in the park.

To keep track of the mine?s 367 underground workings, a place called ?The Secret Room? (named for its blacked-out windows) was built. In it, the entire room was filled with a scale model of the mine?s below the surface workings. Few people knew the room existed while the mine was in operation. Today, visitors to the park can see it in the Visitor Center. The model represents five square miles of underground workings. When the visitors go down the actual shaft in the park, they have journeyed only ?one inch? on the model. Anything past ?two inches? on the model is underwater in the actual mine.