The Teatro dell'Opera di Roma is an opera house. 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. It was originally known as the Teatro Costanzi after the contractor who built it, Domenico Costanzi (1810-1898). It was 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 18 months, on the site where the house of Heliogabalus stood in ancient times, and was inaugurated in 1880 with a performance of Semiramide by Gioachino Rossini.