On Hwy-174, 1 mile East of Grass Valley. The biggest and most technologically innovative of the state’s gold mines, the Empire Mine made Grass Valley one of California’s richest communities in the late 1800s. A far cry from the romantic image of the lone placer miner panning the contents of a river bed, the Empire mine was the epitome of a company-run mine, with 367 miles of tunnels reaching 11,000 feet beneath the ground worked by an army of miners in round-the-clock shifts. The Empire Mine produced 5.8 million ounces of gold and only ceased production in 1956. Many of the buildings, including the opulent English-style mansion belonging to the mine’s owner, remain in the 13-acre park, and a short video film outlines the story of the mine. Throughout May – October at the weekends, volunteer dress in Edwardian clothes and offer free tours of the cottage, estate and demonstrate how the mine used to work, (http://www.empiremine.org).