Custer County Montana (Vacant / Not In Use) has 3 places on the National Register of Historic Places including 2 places of Statewide significance. Significant places include Ismay Jail and Ursuline Convent of the Sacred Heart, Ismay Jail, Northern Pacific Railway Depot and Ursuline Convent of the Sacred Heart.
Some of the country's most noteable architects helped create the Custer County places including Charles S. Haire, W.T. Perham and Winston-Grant. Prominent architectural styles found in Custer Country are Colonial Revival and Renaissance.