The Lateran Complex consists of several high-interest sites: the Basilica, the Treasure Museum, the Baptistery, and the Holy Stairs, which contain the casket of the Papal Chapel of the Sancta Sanctorum.
The Archbasilica of the Most Holy Saviour and Saints John the Baptist and the Evangelist, more commonly known as St. John Lateran, is the oldest church in the western world. Built according to the wishes of Emperor Constantine after his conversion and his victory over Maxentius, it was consecrated in 324 AD. For this reason, it is defined as the mater et caput of all the churches of Rome and the world.