As of 2019, which Italian opera house is the oldest continuously active venue for opera in the world?

The Teatro Reale di San Carlo (Royal Theatre of Saint Charles), as originally named by the Bourbon monarchy but today known simply as the Teatro di San Carlo, is an opera house in Naples, Italy, connected to the Royal Palace and adjacent to the Piazza del Plebiscito. It is the oldest continuously active venue for opera in the world, having opened in 1737, decades before either Milan's La Scala or Venice's La Fenice.

The opera season runs from late January to May, with the ballet season taking place from April to early June. The house once had a seating capacity of 3,285, but has now been reduced to 1,386 seats. Given its size, structure and antiquity, it was the model for theatres that were later built in Europe.