The Montgomery County Rotary Jail is one of those genuinely peculiar things that small American towns sometimes contain: a cylindrical iron jail built in 1882 on a rotating mechanism, so that the entire cell ring could be spun to bring any individual cell to the single door. The theory was that prisoners could never escape and the single guard never had to enter the cells. In practice, the rotation was slow enough that inmates occasionally got fingers and hands caught in the mechanism, and several other design flaws emerged in use.
The jail operated until 1973 and is now a museum, with the sheriff's residence preserved alongside it. The original rotating cell drum is still inside and intact. Guided tours explain the engineering and the often grim history of the people who were held here. It is one of those places that is hard to explain until you stand in front of it.