St Giles' Cathedral (Scottish Gaelic: Cathair-eaglais Naomh Giles), also known as the High Kirk of Edinburgh, is one of three cathedrals in Edinburgh, Scotland. The existing building was begun in the 14th century and extended until the early 16th century; significant alterations were undertaken in the 19th and 20th centuries, including the addition of the Thistle Chapel. St Giles' is closely associated with many events and figures in Scottish history, including John Knox, who served as the church's minister after the Scottish Reformation. The Church of Scotland administers the cathedral.