The estate enter History with Antoine de ROQUELAURE, maréchal de France, loyal companion of Henri IV. A protégé of Jeanne d'Albret, Queen of Navarre, he married in 1611 Suzanne de BASSABAT who brought Castex to him as a dowry.
His influence was great during the six years that he spent with the King: his credited with Henri's conversion to catholicism. He rode in the royal carrosse when the King was murdered by Ravaillac.
Fifty years later, the Gourges family bought Castex who had it for another century. In 1789 it was bought by the Comte de Barrau. His descendants, the Saint Pastou -a very gascon name- still live there.