Not a tree house, but a very cool and old house in the trees. An old settlement in the Scottish Highlands. <---- This place looks magical! Like the home of the three witches in The Black Cauldron or a house in the Shire!
Blue Staircase by Jo Datou on Fivehundredpx This is probably the most famous of the various beautiful staircases of the abandoned Beelitz Heilstätten, located in Beelitz, Brandenburg (Germany). Built in 1898 and has been abandoned for 13 years now.