Originally the main part of the defences of the medieval city, it was transformed in the 15th century by the Duke of Armagnac then in the 17th century by the Duke of Orleans.

Finally, and the beginning of the 20th century, a group of local artists led by Justin-Chrysostome Sanson (1833 – 1910) started the restoration of the old chateau.
Reorganised from 1972, the collections include pieces of Gallo-Roman and Merovingian archaeology, sculptures and religious works and examples of popular arts and traditions. A particular place has been set aside for everywhere from the revolutionary period, nineteenth century paintings and sculptures and twentieth century stamps.