Eilean Donan was garrisoned with Spanish troops during the rising of 1719, but it was surrendered after being attacked by three frigates from the seaward side, and it was blown up from within. It was completely ruined, but restored in the 20th century. The castle is mainly a 13th century wall with a 14th century tower on one end. Other ranges were added later around the courtyard. The main hall of the tower is on the first floor and the basement is barrel-vaulted.
Private rooms are above the hall.
The ghost of one of the soldiers of the Spanish garrison haunts the castle, and Lady Mary haunts one of the bedrooms. Nearly every haunted castle claims to be haunted by Mary, Queen of Scots.