The Estates Theatre is a working opera house that Mozart conducted in, and the room has barely changed since. It is one of the very few late-eighteenth-century theatres in Europe still staging performances, and what you sit in is essentially what was built. It is small and steep, close enough to the stage that a singer needs no effort to reach the back row, and nothing in it was widened or modernised for a larger audience.
It opened on 21 April 1783, with a Lessing tragedy rather than an opera. The Bohemian Estates, the assembly of the kingdom's nobility and towns, bought the house in 1798, and that is where the name comes from. Czech-language performances had already begun here in the 1780s, at a time when German was the language of the stage in this city, and the theatre has carried both repertoires ever since. Prague took to Mozart before Vienna did, and the house has never let anyone forget it.