Suburra

The Italian Wikipedia article on the rione describes the Suburra in Roman times as the low, marshy ground around the Argiletum, on the line of today's via Leonina and via Madonna dei Monti, drained by the Cloaca Massima; its upper part ran towards the Vicus Patricius, today via Urbana. Roma Capitale's own page for the Forum of Augustus explains the great wall behind that forum as a shield against the fires of the Suburra — the Comune's explanation, not the encyclopaedia's. The same Wikipedia article records that an inscription in piazza della Suburra still names the edicola di San Salvatore delle tre immagini ai Monti, a street shrine that no longer stands.