The oldest Christian martyria were built at "a site which bears witness to the
Christian faith, either by referring to an event in Christ's life or
Passion, or by sheltering the grave of a
martyr". Martyria, mostly small, were very common after the early 4th century, when
Constantine and his co-ruler,
Licinius, became the first
Roman emperors to declare
religious tolerance for Christianity in the
Roman Empire (
Edict of Milan, 313 AD). Martyria had no standard architectural plan, and are found in a wide variety of designs. There was often a sunken floor, or part of it, to bring the faithful closer to the remains of the saint, and a small opening, the
fenestella, going from the altar-stone to the grave itself. Later churches began to bring the relics of saints to the church, rather than placing the church over the grave; the first
translation of relics was in
Antioch in 354, when the remains of
Saint Babylas, which were in a
sarcophagus, were moved to a new church. ==Development==