 Evidence of the construction qualities of the stonemasons has remained on the S aisle vaults, which are set on an almost square plan of 4.4 m (14 feet), but built relatively roughly, with thin flagstones and not much attention to keeping the vertices straight.They were probably plastered, with exposed thin ribs.Among the chief benefactors of Holyrood during the four centuries of its existence as a religious house were Kings David I and II; Robert, Bishop of St. Andrews; and Fergus, Lord of Galloway.