The 'tower and fortalice' of Foulis is mentioned in 1587, and documents were being signed there long before that date (e.g. 1491, 1511).

Fragments of an older building and massive foundations were found during the 20th century restoration of the present castle, and a barrel-vaulted chamber in one of the courtyard buildings, with 'inverted keyhole' gun-ports giving a defensive field of fire, date from the 15/16th century.

For some idea of what Foulis was like when it formed a rallying-place for the clan in times of trouble we have only a Mackenzie diatribe in which it figures as 'caisteal biorach, nead na h-iolair' (castle gaunt-peaked, the eagle's nest), in allusion to the chief's heraldic emblem.

Finding his home a semi-ruin after the '45, Sir Harry Munro set about rebuilding. A window in the central tower overlooking the courtyard bears the date 1754, while on the other side, facing the Cromarty Firth, a large Georgian mansion house became the main feature of the castle, with a heraldic panel dated 1777 above the new entrance doorway.

After his father's death in 1781 the work was carried on by young Sir Hugh, but after his young wife was drowned while bathing in the Cromarty Firth (1803) he spent little time in the North. The castle and grounds were neglected and the contents dispersed, and under the 1776 entail the passed in 1849 to a distant and quarrelsome cousin,' Munro of Culrain. There had been a costly litigation, and Foulis was only gradually rescued from its derelict state, but by the time he inherited in the 1880s Sir Hector Munro had made it once more a family home.

With the complete restoration which his grandson, Captain Patrick Munro, and his wife were able to carry out in 1957-59 and 1977-79, Foulis now stands much as it did when it took its present form two centuries ago.