This was the large roman settlement of Alaunium, at the crossroads of the Roman Domitienne Way (Via Domitia) and another Roman road. It was the most important stop on the Via Domitia between Apta Julia (Apt) and Segustero (Sisteron). A "stop" in this case is the equivalent of a stage post, "étape" in French, "mansio" in Latin.)
The site included an auberge, thermal baths, stables an economic infrastructure to support the heavy traffic there, religious sanctuaries, official postal office and other necessary administrative services.
Many artifacts of Antiquity discovered at the site attest to the importance and the extent of Alaunium. A key find is the period inscription, discovered in the 18th century to the west of the chapel. The inscription, including the name Alaunium and dedicated to the devine Alaunis, probably Mercury, can now be seen in the north wall of the monument. Archeological excavations have exposed signs of the ancient buildins and walls all around the Notre-Dame des Anges chapel.