Built on a Friday the 13th, abandoned inside two years
A US Army post on the Bozeman Trail in what is now northeastern Wyoming, begun on Friday 13 July 1866 by four companies of the 18th Infantry under Colonel Henry B. Carrington. It stood for barely two years. The trail it was built to protect ran straight through hunting country the Lakota, Cheyenne and Arapaho were not giving up, and the fort spent its short life under something close to siege.
Other places on the map within a couple of hours of here.