title: Opera house
context: The first public opera house was the Teatro San Cassiano in Venice, opened in 1637. Italy is a country where opera has been popular through the centuries among ordinary people as well as wealthy patrons and it continues to have a large number of working opera houses[1] such as Teatro Massimo in Palermo (the biggest in Italy), Teatro di San Carlo in Naples (the world's oldest working opera house) and Teatro La Scala in Milan. In contrast, there was no opera house in London when Henry Purcell was composing and the first opera house in Germany was built in Hamburg in 1678.
question: What is the oldest surviving opera house?
answers: Teatro di San Carlo in Naples