Building started on Uppsala Slott (Uppsala Castle) in 1549 during the reign of Swedish King Gustav Vasa who intended it as a fortress. Look up from almost any location in Uppsala and you'll see it on the skyline at Kasåsen.
The castle is the location of several major events in the history of Uppsala and Sweden; for example 'the Sture Murders' in 1567 when several noblemen were butchered at the behest of deranged King Erik XIV who had accused them of treason (their clothes are displayed at Uppsala Cathedral). Like many mid-1500s castles in Sweden, bloodbaths, conflict and political plotting were par for the course.
As were fires, which engulfed Uppsala and the castle in 1702 when it virtually burned to the ground. Its remnants were then scavenged for the building of the Royal Palace in Stockholm, which didn't help matters much. The castle façade you see today is faithful to the bright colour it was following its reconstruction in 1740.
The castle now houses three museums, all of them well worth a visit – Uppsala konstmuseum (Uppsala Art Museum), Fredens Hus (House of Peace) and Vasaborgen.
Art and architectural history tours are available in Swedish and English.