A little ways from the gate after which it takes its name, the old foundation of St. John at the Latin Gate commemorates the attempt to execute St. John the Apostle by boiling him alive in a pot of oil.  According to tradition, he survived the attempt unscathed and was sent instead into exile on Patmos, where he received the visions that he later recorded as the book of Revelation.

As can be deduced from first sight of this church, it is very old.  Archeological evidence points to a foundation somewhat before the year 550.  A liturgical celebration of the event here, with the same title as the church, began to be held in 683.  This is traditionally commemorated on 6 May.  In the late eighth century, the basilica underwent a restoration, and in 1191 a more complete rebuilding was undertaken, so that today the sanctuary end of the church is most significant part of the original structure to survive.  In the late medieval period, a loggia was added over the porch, and in the late sixteenth century, a more complete restoration and redecoration took place.  Several later renovations took place over the succeeding centuries, yet nothing remains from these because of a final series of restorations in the early twentieth century.  At this time, nearly all later accretions were removed, bringing the church back to the appearance it had at the time of its rededication in 1191.  As it stands today, the church is a good example of the architecture of that period, while the apse is unique in Rome for being constructed in a polygonal, rather than rounded, shape in the back, a characteristic of Byzantine architecture.  At the time of this church’s construction, Rome was under the control of the Byzantine Empire, and this feature is a lasting remembrance of that time.      

A small round oratory on the main road marks the exact location of the attempted martyrdom