The history of the church dates back to the 324 AD, when it was consecrated by Constantine after his conversion. The Basilica is dedicated to the SS. Salvatore and to the SS. John the Baptist and John the Evangelist and since it is the oldest Christian basilica, it is defined as the mater et caput of all the churches of Rome and of the world. Until early XIV century, when the seat of the papacy was transferred to Avignon, tohether with the Lataran Palace it served as the residence of the pope.
The octagonal Lateran baptistery stands somewhat apart from the archbasilica. According to a legend, Emperor Constantine I was baptized there. The baptistery was for many generations the only baptistery in Rome, and its octagonal structure, centered upon the large basin for full immersions, provided a model for others throughout Italy.
Legend has it that in the 4th century the emperor's mother, Saint Helena, brought to Rome the staircase on which Christ was scourged. Pope Sixtus V brought them to the chapel Sancta Sanctorum, where he gathered the most important relics of Christianity. The weight of this relic is so great that the faithful are required to climb 28 steps on their knees. After traveling this penitential path, pilgrims reach the aforementioned chapel. Here, in addition to the heads of the saints of the first centuries of Christianity (Saints Agnes and Praxeda), there is an acheiropoietos (a word meaning a supernaturally created work), or image of Christ, which is said to have been painted by Saint Luke and the angels.
The beautiful 13th century Cloister of St John Lateran is Vassalletto’s masterpiece, with its twisted marble columns and its ornate sculptures make for a wonderfully peaceful place to explore and meditate.
The Lateran Palace is an ancient palace of the Roman Empire and later was the main papal residence in Rome. From the fourth century, the palace was the principal residence of the popes, and continued so for about a thousand years until the Apostolic Residence ultimately moved to the Vatican. Following the Lateran Treaty of 1929, the palace and adjoining basilica are extraterritorial properties of the Holy See.