King Gustav Vasa built this castle above the cathedral to show his power and his breaking with christianity. His sons made it into a residence fit for a king, who received the county governor there. The great hall, Rikssalen, was used for festivities. The ruins of the initial fortress can also be seen: it was here that Erik XIV imprisoned members of great Swedish families to kill them (the scene is reconstructed with wax figures). The bell, Gunillaklockan, plays an important role in the Sista April celebrations.