St Giles' Cathedral, or the High Kirk of Edinburgh, is a parish church of the Church of Scotland in the Old Town of Edinburgh. The current 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.