Built by Emperor Constantine the Great in 313, San Giovanni in Laterano was the first church to be erected in Rome and the city’s first cathedral. It initially belonged to the Laterani family, but was seized after they had lost their power. Up to the year 1377, when it was moved to the Vatican, the Lateran Palace had served as the papal residency. Throughout centuries, it has been restored a number of times after damage caused by repeated natural disasters, such as an earthquake and a sequence of fires, as well as destruction by the Vandals who plundered it of its vast treasures in the 5th Century.

Measuring 90 metres in length and 50-56 metres in width, the cathedral has simple appearance from the outside, but this is deceptive for the interior hosts numerous works of art of great value. The two-storied portico facade was completed by Alessandro Galilei in 1735. Of note are the 18th-century massive statues of Christ and the saints that top the facade as well as the central bronze doors, Roman originals from the Curia (Senate House) in the Imperial Forum. A Roman statue of Constantine the Great, brought here from the ruins of the Baths of Diocletian, can be seen at the left end of the portico.

Although subject to many modifications over the centuries, the inside of the basilica retains its original plan of a nave flanked by two aisles, terminating in a semicircular apse to the west. However, the current look of the interior is the result of restoration work carried out by Francesco Borromini for Pope Innocent X (1644 – 55). Some elements of the original decoration are still visible too, though in different places that they originally were. Constantine built the baptistery on the northwestern corner of the church, which still stands in its original form. The Cosmatesque pavement (in the nave) was added in the 14th Century, which makes it a late example of this style. At the top of the ornate baldacchino, built above the high altar in 1369, is a reliquary which supposedly contains the heads of Saints Peter and Paul, though these may have been displaced during the French occupation of Rome in the 18th Century. The high altar is reserved for use by the Pope. It holds a relic said to be part of St Peter’s communion table. The Altar of the Holy Sacrament, on the other hand, contains a fragment of a cedar table that is believed to be the one used by Christ during the Last Supper. The marble and bronze columns of the altar probably come from the Temple of Jupiter on the Capitoline Hill. The stercoraria, or throne of red marble where the popes would sit, is now housed in the Vatican Museums, and the currently used episcopal throne dates from the rebuilding at the end of the 19th Century.