Old St. Peter's Basilica
Municipio I, Vatican City · built 320
Old St. Peter's Basilica consisted of the church buildings that stood, from the 4th to 16th centuries, where St. Peter's Basilica stands today in Vatican City. Construction of the basilica, built over the historical site of the Circus of Nero, began during the reign of Roman Emperor Constantine I. The name "old St. Peter's Basilica" has been used since the construction of the current basilica to distinguish the two buildings.
Church data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).