Ireland is an island located in the North Atlantic Ocean separated from Great Britain by waterways. It has a population of over 6.5 million people and its largest city and capital is Dublin. Dublin is located on the east coast of Ireland along the River Liffey and contains important historic buildings like Dublin Castle from the 13th century and St. Patrick's Cathedral built in 1191. The patron saint of Ireland is Saint Patrick who introduced Catholicism to Ireland in the 5th century. Popular sports in Ireland include rugby, football, Gaelic football, and hurling.