Where: Harads, Sweden
Treehouse purists, cover your eyes now: this quirky creation is about as far removed from your run of the mill wooden contraption as you can get. Sweden's Treehotel comprises six uniquely shaped, architecturally designed so-called tree rooms, along with a treehouse sauna and a conference room. The UFO is one of the more popular designs; its ultra modern exterior contains a surprisingly large space that sleeps up to four people. Portholes offer a view of the woods - or planet Earth, if you prefer - below.