The tower house overlooking Sinclair's Bay dates from the 15th Century.
Firefighters and police have launched an investigation into a suspicious fire at a luxury hotel in Caithness.
The emergency services were alerted to the fire in a storage area at Ackergill Tower, near Wick, in the early hours of Sunday morning.
Police Scotland has appealed for information about the incident.
Overlooking Sinclair's Bay, Ackergill is a 15th Century tower house. It was extended in 1850 and later underwent restoration work.
Four years ago it was offered for sale at a price of £5m.