Old North Church, formally Christ Church in the City of Boston, is an Episcopal congregation founded in 1723 and maintained today as a mission of the Episcopal Diocese of Massachusetts. It is the oldest standing church building in Boston and became a national landmark when two signal lanterns were hung in its steeple on April 18, 1775, warning of British troop movements at the start of the American Revolution. The church continues to hold regular worship alongside its role as a National Historic Landmark and museum.