2 Best Sights in Side Trips from Denver, Colorado

During the gold rush days, the Argo Gold Mine and Mill processed more than $100 million worth of the precious metal. To transport the ore from mines in Central City, workers dug through solid rock to construct a tunnel to Central City, 4½ miles away. When completed in 1910, the Argo Tunnel was the longest in the world. During a tour of the mine and mill, guides explain how this monumental engineering feat was accomplished. Admission includes a small museum and a gold-panning lesson.

At the Phoenix Gold Mine a seasoned miner leads tours underground, where you can wield 19th-century excavating tools or pan for gold. Whatever riches you find are yours to keep.