Roman Vestiges in and near the Cathedral Church
of S. Rufino

This is all that's left of the original sarcophagus of bishop St. Rufinus, founder of the Christian community of Assisi, who died in 239. The edge bears the inscription RVFINVS but is it contemporaneous? (For more about the saint, see this Catholic Encyclopedia article.)

Mind you, of most people who lived that long ago, we have even less; on the other hand, another bishop, who died in Milan 150 years later, has fared considerably better (so to speak).

This Roman cistern was incorporated in the fabric of the church; it's in the first chapel to your left (liturgical North) as you walk in.

(Here is a close-up of the masonry of the lower portion.)

Just outside the church, high in the E wall of the piazza, this hard-to‑read Roman funerary inscription (CIL XI.5452) — click on it for a close-up of the text portion — is that of a widower to his wife: a former slave, freed by a woman (in line 2, the backwards C means "of some woman" and is traditionally read Gaiae liberta; now if a man freed a slave, his name got mentioned, of course.)