The origins of the Château de l'Hers, in Châteauneuf-du-Pape on the banks of the Rhône, go back to the beginning of the 10th century. Until the French Revolution it was an enclave of Languedoc in the Comtat Venaissin. Protected as a historic monument since 1973, it has given its name to a winery.
Various elements of the château de l'Hers attest to the occupation of this strategically important location as a control point for river traffic, since late Antiquity at the latest. Several tombs with saddleback roofs form a small 6th-7th necropolis not far from the first known chapel of the château, dedicated to Saints Cosmas and Damian. An excavation of this ruined church found lithic industries, and sherds from antiquity and the Iron Age, fragments of Tegula tiles and a cipolin cladding probably dating to Antiquity were re-used in the masonry. A large number of weapons, coins and medals were found in the area. The tollgate on the Rhône was put in place in 79 AD under Vespasian, according to V. Millet (1864).
There must have been a Roman castrum, probably destroyed in the great invasions. This appeared under the name of castellum de Leri in a 913 charter. It was signed by Louis the Blind and ceded it to Foulques, Bishop of Avignon.