One of the most beautiful Danish castles, Rosenborg, is located in the very center of Copenhagen, surrounded by the King's Garden. The castle was built for the popular Danish king, Christian IV, as a summerhouse (imagine owning a summerhouse like that). More than 400 years ago, this renaissance castle is the centerpiece of the city. With a not-too-big admission fee, you can explore the wanders this place has to offer, even see the Danish Crown Regalia, in the cellar. One of the central attractions here is definitely the long hall, featuring the coronation thrones, and three golden lions.