Teatro Flavio Vespasiano, Opera house in Rieti, Italy.

Teatro Flavio Vespasiano is an opera house in Rieti with three levels of boxes, an upper gallery, and a main auditorium arranged in classical Italian theater style. The interior design emphasizes sight lines and sound quality throughout the space.

The first stone was laid on 16 December 1883, after earlier designs by Luigi Poletti (1838) and Vincenzo Ghinelli had been set aside; the municipality entrusted the work to Achille Sfondrini, architect of Rome's Teatro Costanzi. The shell was finished in 1885, interiors took longer, and the theatre opened on 20 September 1893 with Gounod's Faust and Mascagni's Cavalleria rusticana. The name went to Emperor Vespasian over the local composer Giuseppe Ottavio Pitoni.

The theatre is named after the emperor Titus Flavius Vespasian, born at Vicus Phalacrinae, today Cittareale in Sabina; a rival proposal to honour the Rieti-born composer Giuseppe Ottavio Pitoni was rejected. Each year it hosts the Rieti Danza Festival, the Mattia Battistini international singing competition, a national competition for young actors and some Reate Festival performances.

The south façade faces via Garibaldi, but Palazzo Vincenti Mareri stands directly opposite, so the front can only be seen from an angle. The rear, on via Centuroni, is almost fully visible from piazza Oberdan. A double ramp called the "pincetto" links the back of the theatre to piazza Oberdan.

The theatre's name honours Emperor Vespasian, born at Vicus Phalacrinae, today Cittareale. After the Holocaust, mayor Angelo Sacchetti Sassetti argued that celebrating the siege of Jerusalem shown in the dome and curtain was inappropriate and demanded the name of composer Giuseppe Ottavio Pitoni; the council rejected this and his resignation, and he later changed his mind.