This curved waterside building is called Stopera because it houses both the stadhuis (city hall) and the opera and ballet hall, aka Muziektheater. It opened in 1986. For a peek behind the scenes, take a guided tour on Saturday or Tuesday. Tours are in Dutch but there is an English brochure, and usually English explanations by the guide.
Free lunchtime concerts usually take place from 12.30pm to 1pm on Tuesdays from September to June; doors open at 12.15pm.