Amsterdam has a world-class symphony orchestra, the Royal Concertgebouw Orchestra. Their home is the Concertgebouw, which is across the Van Baerlestraat from the Museum Square. It is considered by critics to be a concert hall with some of the best acoustics in the world. The building contains three halls, Grote Zaal, Kleine Zaal, and Spiegelzaal. Some nine hundred concerts and other events per year take place in the Concertgebouw, for a public of over 700,000, making it one of the most-visited concert halls in the world. The opera house of Amsterdam is located adjacent to the city hall. Therefore, the two buildings combined are often called the Stopera, (a word originally coined by protesters against it very construction: ''Stop the Opera-house''). This huge modern complex, opened in 1986, lies in the former Jewish neighbourhood at ''Waterlooplein'' next to the river Amstel. The ''Stopera'' is the home base of Dutch National Opera, Dutch National Ballet and the Holland Symfonia. Muziekgebouw aan 't IJ is a concert hall, which is located in the IJ near the central station. Its concerts perform mostly modern classical music. Located adjacent to it, is the ''Bimhuis'', a concert hall for improvised and Jazz music.