Kilcashel Stone Fort

Kilcashel Stone Fort is a double court cairn and National Monument located in County Mayo, Ireland, 800m (½ mile) southeast of Kilmovee. The last surviving member of three stone forts in the area, it's estimated to have been constructed between 2,500 and 500BC.

Description
Kilcashel Stone Fort is 30 m in diameter; the stone wall is 5 m thick and 3 m in height. A souterrain is located inside, as well as a bullaun and the sites of two collapsed houses.