The Opéra de Monte-Carlo (French pronunciation: [ɔpeʁa d(ə) mɔ̃te kaʁlo]) is an opera house which is part of the Monte Carlo Casino located in the Principality of Monaco. With the lack of cultural diversions available in Monaco in the 1870s, Prince Charles III, along with the Société des Bains de Mer, decided to include a concert hall as part of the casino. The main public entrance to the hall was from the casino, while Charles III's private entrance was on the western side.

From Wikipedia