The Round Tower of St Mary’s Abbey is located in Ferns, County Wexford. It dates from between the 10th and 12th centuries and stands 60 feet high. The first church at this location was founded in the 7th century by St Aidan. This later became vulnerable to Viking attacks in the 9th and 10th centuries. The Abbey was founded by Diarmait MacMurrough, the King of Leinster, in the 12th century. Diarmait infamously fled to Bristol in 1166 after being stripped of his title and notoriously returned with the first Norman knights from Britain. An unusual feature of this tower is that it is attached to the nave of a Romanesque church. The lower part of the tower is also square. The upper story has defensive slit openings and four square lintelled windows. Round Towers that are attached to churches are rare but not unique – another example being St Kevin’s Church in Glendalough.