The most famous Lateran buildings are the Lateran Palace, once called the Palace of the Popes, and the Basilica of St. John Lateran, the cathedral of Rome, which although part of Italy is a property of the Holy See that has extra-territorial privileges as a result of the 1929 Lateran Treaty. As the official ecclesiastical seat of the Pope, St. John Lateran holds the Papal cathedra in its apse. The Lateran is Christendom's earliest basilica, and is located on one of the 7 hills of Rome, the Caelian.
The inscription at the base of the columns on either side of the central entrance door reads: SACROS LATERAN ECCLES OMNIUM URBIS ET ORBIS ECCLESIARUM MATER ET CAPUT. It translates to "Sacred Lateran Church Mother and Head of All Churches of the City and the World".
The doors to the house of the ancient Roman Senate, the Curia Hostilia, are the main entrance doors to the Basilica de San Giovanni in Laterano. These doors are very impressive bronze doors, decorated with stars and acorns. Most of the original churches in Rome contain Roman artifacts. Some of the churches also are built over original churches. These churches preserve many of the vestiges of the old Roman Empire.
Constantine I gave San Giovanni to the Pope. Attached to the Lateran is a baptistry, one of the oldest in Christendom. The baptistry contains the story of Constantine's victory at the Milvian Bridge in AD 312.