If you've ever wondered where they really locked up the bad guys in the Wild West, check out this fortresslike prison on a bluff above the Colorado River. This prison opened for business in 1876 and, despite the thick stone walls and iron bars, was considered a model penal institution in its day. It even had its own electricity-generating plant and ventilation system. The prison museum has some interesting displays, including photos of many of the men and women who were incarcerated here.