The site originally was a necropolis, and in later constructions was a hospital for the poor and pilgrims, prison, student residence, stables, barracks and presbytery, eventually becoming a museum in 1891.

By the 13th century, at the time the University of Toulouse was created the house had been acquired by the inquisitor Bernard de Caux, who used it as a prison for heretics.

[3] In 1249, the inquisitor offered the house to the abbot of Saint-Sernin in gratitude for his services to the defence of the faith, specifying that the College of Saint-Raymond should be reserved for poor students,[3] as recorded in a 1250 act.

In 1852–1853, during the redevelopment of the Place Saint-Sernin, it was the only building to escape demolition, due to the intervention of Alexandre Du Mège, Prosper Mérimée and Eugène Viollet-le-Duc.

Between 1868 and 1871, it was restored by Eugene Viollet-le-Duc,[5] who removed the remains of the demolished chapel and built a fourth corner turret, added two interior walls and numerous crenellated chimneys that accented the medieval appearance of the structure.

And now it is up to you, gentlemen, to complete it; It is to the public, the supreme judge and without appeal, to decide the future and to grow the work by making it its own and taking as much pleasure as we had to prepare it.

The building was adapted to its new functions by the architect Arthur Romestin, when stairs, partitions and cupboards were altered to create larger exhibition spaces.

The museum was again rebuilt in 1946–1950 by Robert Mesuret, listed as a Monument historique on 11 August 1975,[5] and its upper parts were restored in 1981–1982 to return them to their condition before the intervention of Viollet-le-Duc.

Due to its age, between 1978, and 1982, a new rehabilitation project of the entire museum was launched under the direction of Yves Boiret, then chief architect of French Historic Monuments.

[13] In 1980, the City of Toulouse acquired a neighboring building at 11 rue des Trois-Renards to relocate its offices, technical services and library, to provide and additional 2,500 m2 of exhibition space for the public.

A new redevelopment study was carried out under the direction of Bernard Voinchet, the chief architect of Historic Monuments in 1992, and in 1994, a complete reorganization was arranged by Dominique Baudis, Mayor of Toulouse.

[14] After more than four years renovation the museum reopened to the public on Saturday, 8 May 1999, having been restored to its original 1523 appearance, while a part of the ancient early Christian necropolis, dating from the fourth and fifth centuries, has been excavated.

Several civilizations of the Mediterranean are represented: Cypriot and Etruscan pieces, Greek and Italian vases from the eighth to the first century BC and Hellenistic terracotta figurines.

In the basement are the early Christian necropolis, developed at the time the first basilica housing the body of Saint-Saturnin was built, sarcophagi and funerary inscriptions and a lime kiln.