This document lists some of the most beautiful opera houses in the world, including the Romanian Antheneum in Bucharest, Mariinsky and Mikhailovsky opera houses in St. Petersburg, La Fenice in Venice, Teatro di San Carlo in Naples, La Scala in Milan, and the Palais Garnier and Metropolitan Opera House in Paris and New York City respectively. It also mentions several other opera houses located in cities across Europe, North America, South America, and elsewhere.