More on Saint John the Lateran

" Ascension" by Cavalier d' Arpino

From the south transept head above the Blessed Sacrament

Before The Lateran Votive Church became the first place of public Christian worship, it was the Lateran Palace, held by prominent patriarchal family of Rome, the Laterani. At some point during Nero’s reign as emperor, it was confiscated. The Palace eventually fell in the hands of Constantine the Great. After Constantine’s conversion, in about 313, he gave the church to the Bishop of Rome, Pope St. Miltiades. The palace was converted and extended, eventually becoming the cathedral of Rome, the seat of the popes as bishops of Rome.

The main Façade is built in1732-1735 and was created by the Florentine Alessandro Galilei, architect to the nephew of Pope Clement XII, who oversaw the completion of the façade as archpriest of the Lateran.

I don’t know how long the Lateran church was the seat of the Holy Father. As reference, though, work on Saint Peter’s Basilica didn’t begin until April of 1506. The Basilica of Saint Peter was completed in 1626