Dun Aengus is a fort situated on the edge of a cliff at a height of 100 meters overlooking the Atlantic on the Aran Islands, Inishmore. It consists of a series of concentric circular walls, the innermost; the citadel encloses an area approximately 50 meters in diameter with 4m thick walls of stone. These walls have been rebuilt to a height of 6m and have wall walks, chambers, and flights of stairs as well.
O'Brien's Castle on Inis OÃrr in the Aran Islands was built in the 14th century. The castle was taken from the O'Briens by the O'Flaherty clan of Connemara in 1582.
Dun Eochla and Dun Eoghanachta are ringforts located inland of the island and can be seen from the main road.
Clochan na Carraige is a beehive hut. The structure is unusual because the outside is circular but the inside is rectangular.
