From the royal abbey founded around 485-557 by Clotaire the 1st,son of Clovis, for St Médard, bishop of Noyon,the crypt is the only part of the main church not to be demolished following the sale of the abbey as a national property in 1791.

It was a powerful abbey, a worship and pilgrimage place where St Sebastian’s relics were kept around 826 and the bishop St Médard’s grave, Clovis’s and his son’s as well as Sigebert’s were housed there.

Nowadays in the precinct of the abbey is an Educational Centre for Children called “La Cordée”