Kastellet was constructed between 1662 and 1725 and was a cornerstone of King Christian IV’s defenses of Copenhagen. It continues to be in use by the army and within you will find long, crimson brick, slate-roofed structures, a parade floor, and in many cases a Dutch-style windmill. A check out https://socialevity.com/story18691419/facts-about-things-to-do-copenhagen-reddit-revealed