Saluda River Tree House. A very nice two story construction with a post-modern touch. The man who lived in the house designed and built it himself. The lower deck is a great place for overlooking the beautiful area and the river. What is more, this tree house even used to have power and water, so the owner could take a shower or cook meal in the kitchen/dining room.
(Source: Flickr / marc50, via dbmurphy)