Approximately one mile south of the Colosseum is the Archbasilica San Giovanni in Laterano. Built in 314 AD by Emperor Constantine the Great, it is the official ecclesiastical seat of the Bishop of Rome (The Pope). This is the first Christian Church built in Rome, and in the whole world. As such, it is designated as an arch-basilica and as the Mother Church of all churches. The Archbasilica San Giovanni ranks above all other churches within the Catholic community, including St. Peter's. It was built over the remains of a second century fort of the Mounted Imperial Guards and over the first century palace of the Family Laterani (thus the reason for the name San Giovanni in Laterano).