St. Stephen of the Abyssinians
Vatican City, Vatican City · built 801
St. Stephen of the Abyssinians (Santo Stefano degli Abissini) is an Ethiopian Catholic chapel located in Vatican City. The church dedicated to Stephen the Protomartyr is the national church of Ethiopia. The liturgy is celebrated according to the Alexandrian rite of the Ethiopian Catholic Church. It is one of the only standing structures in the Vatican to survive the destruction of Old St. Peter's Basilica (c.1505), and thus it is the oldest surviving church (in terms of architectural history) in Vatican City.
Church data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).