Trevi is the 2nd rione of Rome, Italy, identified by the initials R. II, located in Municipio I. The origin of its name is not clear, but the most accepted theory is that it comes from the Latin trivium, because there were three streets all leading to the current Piazza dei Crociferi, a square next to the modern Trevi square. Its coat of arms is made of three swords on a red background.

Municipio I is an administrative subdivision of the municipality of Rome, encompassing the centre of the city.