Rathcroghan (Irish: Ráth Cruachan, meaning "ringfort of Cruachan") is a complex of archaeological sites near Tulsk in County Roscommon, Ireland. It is identified as the site of Cruachan, the traditional capital of the Connachta. While it is debatable whether this was a place of residence, it had huge importance as a cemetery and also hosted some of the main ritual gatherings in ancient times. It is an important site in Irish mythology, in particular as the seat of Ailill and Medb, king and queen of the Connachta in the Ulster Cycle.