St. John Lateran, as I understand it, means St. John of the Walls. And indeed the old Roman city walls are just outside the basilica.
Probably the Porta Maggiore immediately outside the basilica. If so, it is the most imposing of all the gates, and was constructed at the time of Claudius.
Almost immediately adjacent to the above, this part of the wall now is the beginning for Via Appia, the modern day replacement for the mother road of the Roman Empire. The Via Appia starts on the other side (outside of the city) of the arches. This is not the same Via Appia as the ancient Romans knew.
St. Francis of Assisi, constructed in 1926 it would appear. This is immediately across the street from the basilica.
The outside of the Roman walls. Our bus was parked down the far end.