Most recently the home of the late Capt. Hay of Delgatie, Feudal Baron, the Castle has largely been in the Hay family for the last 650 years. It was taken from the Earl of Buchan after the Battle of Bannockburn in 1314, when Robert the Bruce routed the invading English army. Mary Queen of Scots stayed at Delgatie for three days after the Battle of Cirrichie in 1562. Her bedchamber is on view to the visitor.

Like many Scottish castles, Delgatie was rebuilt in the 16th century. The invention of the siege gun necessitated greater fortifications, and the 1570 rebuilding provided 8-14 feet thick walls. The main tower dates from about 1100, while its final extension with the battlement walk above the string course was completed in 1579. Both wings were added in 1743 with the chapel and dovecote on the west and the kitchen and servants' quarters on the east.

Some of the rooms still boast their original 16-century painted ceilings, which are considered some of the finest in Scotland. Strange animals are depicted -- some with human heads thought to represent the actual inhabitants of the time.

The turnpike stair of 97 treads is reputed to be one of the widest in Scotland, measuring over five foot. It is unusual for being built within the thickness of the wall.