Haga is a castle north of Stockholm in Sweden. A castle is a defensive structure seen as one of the main symbols of the Middle Ages. ('stɔkhɔlm is Sweden 's Capital and its largest City. It is the site of the national Swedish government, the parliament, and the "Sverige" redirects here For other uses see Sweden (disambiguation and Sverige (disambiguation. King Gustav III spent a lot of time at Haga. Gustav III ( – 29 March 1792) was King of Sweden from 1771 until his death