The Empire Mine State Historic Park is a state park and historic site in Grass Valley, California. It preserves and protects one of the oldest, longest, richest, and deepest gold mines in the state.

Covering 777 acres of area, the Empire Mine State Historic Park offers a lot of things to its visitors. For one, it is rich in history, being built in the late 1800s and one of the most noted Gold Rush mines in all of California. The site features the mine with its 367 miles of underground passages, the famous ?Secret Room? which is an accurate scale model of the entire mine, a museum, and the historic 1890s estate of William Bourn, Jr. There are also some 13 acres of scenic gardens at the site and on weekends of May through October costumed interpreters roam around the park.