Largest Tree House
This 6,000 sq ft. tree house is the world's largest treehouse. It is located on the grounds of Alnwick Gardens, about 95 miles north south of Edinburgh, Scotland, the leviathan soars 56ft. above the ground and is connected with 4,000-square-feet of suspended walkways. There's a 120-seat restaurant plus wobble bridges, classrooms, turrets etc.
"The unique dining experience on offer in The Treehouse is nothing if not unusual. The roaring log fire in the centre of the room, the living tree complete with green leaves growing through the restaurant, the fascinating craftsmanship which has created screens from fallen branches and the dimmed lighting combine to create an other-wordly, magical environment. The delicious menus include a fantastic range of locally sourced produce, helping The Garden encourage and support local producers."
If you are more adventurous, then here's another variety of tree house:
Longest Bridge in the World