The Teatro dell'Opera di Roma (Rome Opera House) is an opera house in Rome, Italy. Originally opened in November 1880 as the 2,212 seat Costanzi Theatre, it has undergone several changes of name as well modifications and improvements. The present house seats 1,600.
The Teatro dell'Opera was originally known as the Teatro Costanzi after the contractor who built it, Domenico Costanzi (1810-1898). It was privately financed by Costanzi who commissioned the Milanese architect Achille Sfondrini (1836-1900), a specialist in the building and renovation of theatres.
The opera house was built in eighteen months, on the site where the house of Heliogabalus stood in ancient times, and was inaugurated on 27 November 1880 with a performance of Semiramide by Gioachino Rossini.