Auchans Castle, House, House of Auchans[2] or Old Auchans, is a mock military mansion, Category A listed,[3] T-plan building of a late 16th century date converted to the L-plan during the early-to-mid-17th century; its ruins stand about 1 km W of Dundonald, South Ayrshire, Scotland. Parish of Dundonald. It was held at various times by the Wallace, Cochrane and Montgomerie families.