Ardtornish Castle stands on a promontory sticking out into the Sound of Mull. It is described as a 'hall house' of probably two storeys, with the principle residence being on the upper floor. The castle was once a residence of the Lords of the Isles. It was part of a chain of eight castles, on both sides of the Sound of Mull, which made it possible to transmit a beacon signal from Mingary Castle (Ardnamurchan) to Dunollie Castle (near Oban), a distance of over 30 miles. Today the castle is in ruins after plans to restore it in the 19th century failed.