According to Tertullian, as quoted by Saint Jerome, in the year 92, St John the Evangelist survived martyrdom at Rome under the Emperor Domitian by being immersed in a vat of boiling oil, from which he emerged unharmed.

The tradition for the building of the Basilica of St. John at the Latin Gate places its construction during the pontificate of Pope Gelasius I (492–496).

This is consistent with the oldest of the roof tiles, which have the imprint of a taxation stamp for the Ostrogoth King and ruler of Italy Theodoric the Great (reigned 493–526).

[2] Michel de Montaigne, a French philosopher and prominent essayist of the 16th century, noted in his journal that, On my return from Saint Peter's I met a man who informed me...that on this same day [March 18, 1581] the [Holy Week] station was at San Giovanni Porta Latina, in which church a few years before certain Portuguese had entered into a strange brotherhood.

The well-head, from the time of Pope Adrian I, has a double row circular design around its barrel and a Latin inscription completely around its crown: and a quote from the Prophet Isaiah: and the name of the stone-carver: The interior of the Basilica is divided into three naves, divided by two rows of columns on which rest semi-circular arches.

Occupying the ledge of the central window is a carved wooden crucifixion scene including Saint John the Evangelist and the Blessed Virgin Mary.

After this work, another search along the face of the central nave revealed the presence of a full circle of medieval frescoes.