Ireland is the third-largest island in Europe and the twentieth-largest island in the world. To the east of Ireland is Great Britain, separated from it by the Irish Sea. There are three World Heritage Sites on the island: the Brú na Boinne, Skellig Michael and the Giant's Causeway. A number of other places are on the tentative list, for example the Burren and Mount Stewart. Some of the most visited sites in Ireland include Bunratty Castle, the Rock of Cashel, the Cliffs of Moher, Holy Cross Abbey and Blarney Castle. Historically important monastic sites include Glendalough and Clonmacnoise, which are maintained as national monuments in the Republic of Ireland.
