Levan is a 14th century keep, later extended with an additional tower to form the present L-shape. The feel of a medieval defensive structure - turnpike stair, turret, and gun loops - contrasts with the warm and sophisticated home created by the present owners. It is set, a little incongruously, between a housing estate and a tumbling woodland burn. From the parapet walkway there are stunning views over the Firth of Clyde, to the Holy Loch and Ben Lomond beyond.

Mary of Guise sentenced one chatelaine, Marion Montgomery to death for murdering her tenants, but the sentence was commuted to house arrest. On return from military service her husband was so appalled to hear of her disgrace that he starved her to death. She still frequents her ancient cell.