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. Original Teatro Costanzi: 1880 to 1926 The Teatro dell'Opera was originally known as the Teatro Costanzi after the contractor who built it, (1819–1898). 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 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. Designing the theatre, Sfondrini paid particular attention to the acoustics, conceiving the interior structure as a "resonance chamber", as is evident from the horseshoe shape in particular. With a seating capacity of 2,212, the house had three tiers of boxes, an amphitheatre and two separate galleries, surmounted by a dome adorned with splendid frescoes by Annibale Brugnoli. Costanzi was obliged to manage the theater himself. Under his direction, and despite financial problems, the opera house held many world premieres of operas, including Cavalleria rusticana by Pietro Mascagni on 17 May 1890. For a brief period the theatre was managed by Costanzi's son, Enrico, who gained renown by organizing another great premiere, that of Tosca by Giacomo Puccini on 14 January 1900. In 1907, the Teatro Costanzi was purchased by the impresario (1871–1955) on behalf of the Società Teatrale Internazionale e Nazionale (STIN). In 1912 Mocchi's wife, Emma Carelli, became the managing director of the new Impresa Costanzi, as the theatre was later known, following various changes in the company structure. During the fourteen years of her tenure, major works which had not been performed before in Rome (or even in Italy) were staged. These included La fanciulla del West, Turandot and Il trittico by Giacomo Puccini; Parsifal by Richard Wagner; Francesca da Rimini (Zandonai) by Riccardo Zandonai; Boris Godunov by Modest Mussorgsky; Samson et Dalila by Camille Saint-Saëns and many others. Diaghilev's Ballets Russes also performed. Restructured Teatro Reale dell'Opera: 1926 to 1946 In November 1926 the Costanzi was bought by the Rome City Council and its name changed to Teatro Reale dell'Opera. A partial rebuilding ensued, led by architect Marcello Piacentini and lasting fifteen months. The