The old Macoupin County jail looks more like a little fortress than a civic building. Built in 1869, it used a "cannonball" method: stones were hollowed out and packed with leftover Civil War cannonballs, making it nearly impossible for prisoners to dig through the walls.
The jail served the county until 1988. Its Gothic Revival details and strange construction story make it a natural companion to the courthouse across the square. Check current opening times before counting on an interior visit.