St. Helen the Constantine’s mother, began to build up the Basilica in 326. It was completed around 330 and dedicated in 339. In 529 the Constantinian Basilica was destroyed during the Samaritan Revolt. In 531 it was rebuilt by Justinian as St. Mary Theotokos.
See:
- Lorenzo Nigro, Bethlehem in the Bronze and Iron Ages, in the light of recent discoveries by the Palestinian MOTA-DACH, Vicino Oriente XIX (2015), p.10 - https://www.academia.edu/22280922
- http://www.bethlehem.custodia.org/default.asp?id=455