Treehotel, Sweden

As much an art project as a lodge, Treehotel is a collection of distinctive "hotel rooms" designed by noted Scandinavian architects. Each is located halfway up the trunk of an old growth pine in the middle of a forest. Each room is a unique design – one is a UFO shape; another is constructed from mirrors. Dining is hyper-local and activities vary based on season: though the chance to catch the northern lights is a winter-only thrill. Visit during the summer, when bright nights are spent on horseback. [From $507/night;]