Château Kirwan is a Troisième Grand Cru Classé in the commune of Margaux. The late 18th century château was built by Mark Kirwan, a prosperous Irish businessman who combined two small adjoining vineyards in the village of Cantenac. The estate is mentioned in Thomas Jefferson's famous book on wine after his trip to Bordeaux in 1787, noting that “Château de Quirouen” was in the 2nd category, along with “Ségur” and “Lynch”.