This 90ft tower is located on the grounds of St Columba`s church and was built in the 10th century as part of the early Christian monastery. It was a bell tower, but would have been used as a lookout tower and as a place of refuge during attacks from either local or Norse raiding parties. The tower has a long and troubled history, including murder of local chieftains to the theft of the Book of Kells in 1007.