In the 1st century BC, the site was originally a large settlement center located near the ford, allowing the Cahors (Divona)-Toulouse (Tolosa) road to cross the Aveyron River. In 961, Raymond I, Count of Rouergue bequeathed to the abbey of Moissac, the lands, castles and churches of Cos.
In 1628, the Wars of Religion left the Catholic population of Ardus battered and the buildings of Ardus and Cos (mill, castles, churches) in ruins. François Duval took the title of Baron de Lamothe in 1734, he built the present castle on the banks of the Aveyron and became owner of the mill. In 1737, he founded an earthenware factory, the first Montalban establishment to obtain the title of Manufacture Royale in 1739.