This building, weathered over the centuries, is not far from the banks of the Basse, in the centre of suburbs which have disappeared today, which included tanneries and old leather trimming works, weavers or tanners who made up the traders of Roussillon at that time. From the same epoch as the Bastille, it was built around 1368, upon the orders of the young Don Juan of Aragon, by the overseer Guillaume Gitard, who used a very resistant element for this building, « pozzolana « or artificial volcanic ash made into bricks piled up and mixed with lime. All the sheathing was in brick.
One of the last remains of the fortified remparts of the town.
Louis 11th transformed it in 1478 into a state prison. The windows were fitted with railings, the drawbridge was taken out and, to ensure exit to the town via the suburbs, a small castillet was built next to this primitive building.. This became the door of Notre Dame of the bridge, built in 1481 by an architect from Montpellier. Charles Quint then Vauban reinforced the whole site, which became a true defence bastion. When the town remparts were demolished in 1904, the Castillet remained alone. Even after such mutilation, this curious building has remained very beautiful thanks to its colour and its lines. Since then, it has become a very interesting Museum of Popular Arts and Traditions in Roussillon christened Casa Pairal. The Castillet is the emblematic monument of the town.