It was originally part of the canons' convent. The enclosure counted a cloister, a refectory, a chapter room, a dormitory, kitchens, store rooms, ... There was also a fountain, which still existed in the 19th century at the time of the restorations.
All those buildings were sold as national goods in 1791 and razed at the same time as the old Bishops' Palace in 1795. A small vineyard and an orchard occupied the site until the Grand Theatre took the place at the beginning of the 20th century. There are now poor remains of the cloister.
So it was built at the same ground level as the cathedral, but the ground was heightened in the 16th century, and the tomb disappeared ! This chapel was neglected and almost forgotten, serving as the sacristy.
That's what saved it from destruction and plunder.
The Bishop is standing on his sarcophagus and the burial ceremony is represented by a canons' procession and two angels flying away to the Skies with Radulphe's soul.
Radulphe, whose name was in fact Razouls, climbed under Saint Louis' reign all the rungs of an ecclesiastic career, right up to the episcopate.
The Chapel was first built to serve as the infirmary of the monks. It became a tomb only a few years after Radulphe's death in october 1266.