Byzantium is the oldest memorial place for Hungarian Christianity. The city of emperors has seen many Hungarian delegations even before the conquest of the Carpathian Basin. Leaders Tormás and Bulcsú used this baptisery in 948 in order to become Christians, while agreeing on a 5-year peace treaty with Constantine VII Porphyrogennetos. A couple of years later, Gyula from Transylvania also converted to Christianity here, returning with a bishop. Their example was most probably followed by others as well. According to art historians, the baptisery is as old as the main building.