The Hidee Mine, just south of Central City off Highway 119, offers guided underground tours that get you deep into a real working gold-mining operation. The tour involves walking several hundred feet into the original adit, watching a live demonstration of the rock drill, and chipping a sample of ore from the vein to take home — which usually contains visible gold and pyrite.
Hard hats and warm layers are required (the mine stays around 50°F year-round). Tours run regularly through the summer; in winter the schedule is reduced. It is one of the better mine tours in the area for understanding the actual mechanics of hard-rock mining, as opposed to the more sanitised museum-style operations elsewhere in the historic district.