copenhagen, denmark. kastellet citadel, one of the best preserved fortresses in northern europe

17th century christiania copenhagen danish royal family denmark hans christian andersen kastellet kobenhavn little mermaid northern europe scandinavia viking adventure architecture art galleries atmosphere bastion charming citadel cobblestone streets colored sky colorful buildings defensive downtown famous place fortress glowing streetlights heritage historic historical history holiday iconic idyllic landmark lively mustvisit outdoor picturesque overcast pedestrian walkway pentagon romantic sightsview tourist destination touristic area twilight vibrant voyage denmark one preserved fortresses xvii form bastions corners