Opening in 1637, the Teatro San Cassiano in Venice was the world's first public what?

The Teatro San Cassiano in Venice was the world’s first public opera theatre, inaugurated as such in 1637. The first mention of its construction dates back to 1581. The name with which it is best known comes from the parish in which it was located, San Cassiano (Saint Cassian), in the Santa Croce district (‘sestiere’) not far from the Rialto.

It was owned by the Venetian Tron family and was the first ‘public’ opera house in the sense that it was the first to open to a paying audience. Until then, public theatres (i.e., those operating on a commercial basis) had staged only recited theatrical performances (‘comedies’ or ‘commedie’) while opera had remained a private spectacle, reserved for the aristocracy and the courts. The Teatro San Cassiano was, therefore, the first public theatre to stage opera and in so doing opened opera for wider public consumption.