Inis Cealtra (Irish for Holy Island), in Lough Derg in County Clare, is one of the most famous monastic sites in Ireland. Its many attractions include a well preserved Round Tower, the ruins of six churches and a bargaining stone where marriage vows are still renewed.Pilgrims from all over the world come to visit the Monastic site on Holy Island or Inis Cealtra, in Lough Derg County Clare. Boat tours depart from Mountshannon to bring you to Holy Island.