St Giles' Cathedral is the principal place of worship of the Church of Scotland in Edinburgh. The site on the Royal Mile has been a religious focal points for over 900 years. The present church with its distinctive crown steeple dates from the late 14th century, though it was extensively restored in the 19th century. 

Simpson & Brown carried out extensive work at the category A-listed St. Giles Cathedral over a period of twenty years. Works included the reordering of the interior along with extensive stone and lead repairs to the external fabric. The crypt was converted to form the Lower Aisle Restaurant and kitchen. The link between the church and its new basement facility is via a new stone stair. Alterations were also made to form the Cathedral shop, offices and choir rooms.