Cruachan (Cruachu, Cruachain, Ráth Cruachain) is the ancient capital of the kingdom of Connacht, and the seat of Ailill and Medb in the Ulster Cycle of Irish mythology. Its site is now known as Rathcroghan , a low mound surrounded by a complex of archeological sites near Tulsk in County Roscommon. A standing stone there is said to mark the grave of Dathí, one of the last pagan High Kings of Ireland.