After having studied the circumference of the circular prison, archaeological surveys have now been undertaken in the cellars and courtyards of the current museum. Archaeologists hope to find remains from the Middle Ages, linked to the construction of Nicolas Rolin's house.
Several medieval burial sites have been found underneath the Place Saint-Louis. They were probably part of the parish cemetery, next to the site of the church Notre-Dame-du-Châtel . They did not contain any additional material (no vase, no traces of clothing or jewelry). Radiocarbon dating will give us a more precise indication on the approximate date of these tombs.