Saint John's Point or St. John's Point (Irish: Rinn Eoin) is a cape at the southern tip of the Lecale peninsula of County Down Northern Ireland, separating Dundrum Bay from Killough Harbour, which forms its northern extremity. The cape is mostly surrounded by the Irish Sea and derives its name from a now ruined church dedicated to Saint John, being recorded here since at least 1170. A well known beacon in the north-eastern Irish Sea, St. John's Point Lighthouse, built in 1844, sits near its southern tip and, at 40 m (130 ft), is the tallest lighthouse in Ireland (the Fastnet Lighthouse, though taller, is offshore).