Kastellet was crafted amongst 1662 and 1725 and was a cornerstone of King Christian IV’s defenses of Copenhagen. It remains to be in use by the military and inside there are very long, purple brick, slate-roofed structures, a parade floor, and in many cases a Dutch-model windmill. Why it’s magnificent: https://bookmarkmiracle.com/story18480964/about-things-to-do-copenhagen-rainy-day