Teatro dell'Opera di Roma (Teatro Costanzi)

The Teatro dell'Opera di Roma publishes its own history of the building. It was built in 1879 for Domenico Costanzi (1810-1898), who gave the work to the Milanese architect Achille Sfondrini (1836-1900), and it went up in eighteen months on ground anciently occupied by the villa of Elagabalus. It was inaugurated on 27 November 1880 with Rossini's Semiramide, conducted by Giovanni Rossi before the sovereigns. Sfondrini designed the house as a cassa armonica, a sounding box, which is why the auditorium is a horseshoe; it held 2,212 seats in three tiers of boxes, an amphitheatre and a gallery, under a dome frescoed by Annibale Brugnoli.

Four operas had their world premieres here. The theatre's own account puts Cavalleria rusticana, on 17 May 1890, and L'amico Fritz, on 31 October 1891, under Domenico Costanzi's management, and Tosca, on 14 January 1900, and Le Maschere, on 17 January 1901, under the direction of his son Enrico. Management passed to Walter Mocchi in 1907 and to Emma Carelli in 1912. The Comune di Roma bought the theatre in 1926, renamed it the Teatro Reale dell'Opera and had it remodelled by Marcello Piacentini; it closed on 15 November 1926 and reopened on 27 February 1928 with Boito's Nerone, conducted by Gino Marinuzzi. It was rebuilt again in 1958.

Italian Wikipedia's article on the rione dates the building 1874-80 and credits Sfondrini and Piacentini jointly. The theatre's own account contradicts that and puts Piacentini's work in 1926-28; this guide follows the theatre on its own dates. Neither the theatre's history page nor its contacts page publishes a street address, so the square is given here and no number.