Once a fortress of great strength on a promontory above the meeting of two rivers, Airlie (or Erroly) Castle consisted of a 15th-century tower and courtyard. A deep ditch cut off an angle of land between two rivers, and beyond this was a massive curtain wall with a strong gatehouse. The gatehouse, which had a portcullis, was altered in the 16th century with the addition of a conical-roofed caphouse. Little else of the old castle remains.