Dating from 1455, Orchardton Tower is a unique fortified tower house. It is the only surviving near free-standing late medieval circular tower in Scotland. Circular towers were common in the strongholds of the 1200s, but by the 1400s had been superseded by square and rectangular towers.

The 11 metre high, four storey structure was used solely as a residence and would have stood within a fortified barmkin containing other ancillary buildings.