Bavay : AD 156 Plot. A Building with Hypocausts Belonging to the B Antique Urban Network. A minor intervention prior to the construction of a private building allowed to unearth the remnants of a vast hypocaust and of a contiguous underfloor space. The excavated area does not allow to assess the total extent of the building, but ancient excavations, carried out about ten metres away had revealed built remnants probably connected to our latest discoveries. This vast set was built above an older building dating back to the first third of the Ist century whose walls were dismantled in order to erect the building with hypocaust. It fits in with the B urban network which is, in all likelihood, the original street pattern of the antique town.