The Grass Valley Museum occupies part of the old Mount Saint Mary's Convent complex — a Victorian institution that was the oldest continuously operating Catholic school west of the Mississippi before it closed. The museum focuses on local history from the Gold Rush through the 20th century, with exhibits on mining, the immigrant communities that settled Nevada County, and the town's Cornish heritage.
The Cornish connection is a particularly worthwhile thread. Many of the hardrock miners who worked the Empire and North Star mines came from Cornwall, where deep tin mining had developed techniques that translated directly to the gold fields. Their food (the pasty), their customs, and their community organisations left a lasting mark on the town's culture.