The Basilica of Our Lady in Trastevere (Italian: Basilica di Santa Maria in Trastevere) is a titular minor basilica, one of the oldest Churches of Rome, perhaps the first in which Mass was openly celebrated. The basic floor plan and wall structure of the church date back to the 340s, The first sanctuary was built in 221 and 227 by Pope Callixtus I and later completed by Pope Julius