The old jail is the oldest building in Ellsworth. Earlier jails were temporary structures like cages. At other times, prisoners were housed in private homes.

This jail was authorized on April 2 1872, with the lower floor designated as the jail and the upper floor to be used as court rooms. (Use of the upper floor for any purpose has not been verified through historic records)The structure was of limestone construction, 36 by 50 feet.

In 2003, the historic treasure was the beneficary of a stabilization project. A fund raising campaign provided the necessary resources to place steel framework on the interior to stabilize the structure and prevent further shifting of the walls. Although the upper floor had collapsed, the walls with cell windows remain intact. Loose limestone was removed and reset to ensure the original physical appearance. In October 2003, the building was rededicated and stands ready to greet visitors seeking to experience the image of the wild, wickedest cowtown of the West.