Exterior, Wood Siding Material, and Cabin Building Type Taking inspiration from Arlberg Valley, Austria to classic Nordic materials, the Troll Hus certainly adds a European touch to the California landscape. “The inspiring concept is that of a treehouse that, as if suspended between treetops, seamlessly and ingeniously blends with its surroundings.” Casper says.  Photo 1 of 7 in Here's What Norse Mythology and Modern Architecture Have in Common