I was introduced to Assisi, a beautiful Umbrian hill town where St. Francis was born, by a good friend of mine.

The Basilica Of St. Francis is one of the earliest major gothic buildings in Italy. The upper church is decorated with frescoes by Giotto, and was severely damaged in an earthquake in 1997. The tomb of St. Francis can be found in the crypt.
The Porziuncola dates from the ninth century and is the place where St. Francis founded the Franciscan order. Los Angeles is named after the Porziuncola, just as San Francisco is named after St. Francis.

Spello is another hill town not far from Assisi.

On the same trip, I passed through Rome, for the fourth time (see first, second, third).

Much of Santa Maria Maggiore dates back to the fifth century.
St. John Lateran is the seat of the pope and therefore the cathedral of Rome (i.e. above St. Peter's Basilica). It lies on Vatican territory, rather than Italy.