Doon Fort is an ancient ring fort hidden away on Doon Lough near the coastal village of Portnoo in County Donegal. It dates from the 5th century AD and was probably built as a place of refuge. Its walls stand 15-feet high and are 11-feet thick. The fort covers most of the island which was partially constructed with the use of large stones at the base like a crannog, while the walls were built of smaller size stones. It is sometimes referred to by the locals as ‘The Bawan’ or ‘O’Boyle’s Fort’ as it became their stronghold in the 16th century. It was also the scene of the murder of Conor O’Boyle in 1530 who was slain by a rival O’Boyle family member. Its construction methods are similar to other Irish dry-stone wall forts such as Dun Aengus on the Aran Islands, Grianan of Aileach in Donegal and Staige Fort in Kerry. This national monument is now on land belonging to a friendly local family who until recent times used it as a walled garden. During the holiday season they have small boats available for hire.