The magnificent Theatro Municipal (theatromunicipal.rj.gov.br) is the home of Rio's opera, orchestra, theater and ballet. Campaigning for the theater, the headpiece of Cinelândia square, began soon after Brazil's declaration of the Republic in 1889 (the end of the monarchy). Although it wasn't until 1905 that construction on the theater, designed in the style of the Paris Opera by Brazilian Francisco de Oliveira Passos and Frenchman Albert Guilbert, began. The building was completed in just 4½ years – possibly a Brazilian record – and opened in 1909 with a capacity for 1739 spectators (later expanded to 2361). Its lavish interior contains many beautiful details – including the stage curtain painted by Italian artist Eliseu Visconti that features portraits of 75 major figures from the arts, such as Carlos Gomes, Wagner and Rembrandt.
You can visit for guided tours lasting 45 minutes on Tuesdays to Fridays (R$20, no prebooking). It's also well worth coming for a performance — they even occasionally offer tickets for R$2 to R$10 (watch its Instagram).