At the outset, there was only one Château Sémeillan, which was one of the oldest and greatest growths of Listrac-Médoc. The "Le Médoc et ses vins" guide, created by Edouard Féret and Théophile Malvezin and published in 1876, referred to a production of 90 barrels. The co-owners at the time were the Barons of Castelnau and Drillon. Viscountess du Pavillon purchased the estate at the beginning of the 20th century, then sold it to Mr P.A. Hostein in 1925. In the 1932 classification, Château Sémeillan was ranked in the Crus Bourgeois de Listrac category. When Mr Hostein died in 1938, the estate was divided among his three daughters, Mrs Mazeau, Mrs Balleu and Mrs Bibian. Château Sémeillan Mazeau was created as a result. True to its original terroirs, the Sémeillan Mazeau vineyard is still on the gravel plateau of Champ de la Grêle today. As the highest point in the Médoc, the quality site benefits from a exceptional panorama, offering a clear view of both banks of the Gironde river.