Tree houses aren't just for kids anymore. Here are 15 of the coolest tree houses in the world, from a 6,000 sq ft tree house to a suspended 'nest' tree house.

Know of other recycled design or amazing architecture projects? Be sure to list them in the comments below!

These seven trash-obsessed artists may have had a similar starting point but have managed to create an inspiring variety of art from abandoned refuse.

What would it take to get you to see a well-known building material in a new light?

Feeling a little cramped in your thousand square foot Manhattan apartment? Got a few extra million to blow?

From seed vault to military hideouts and diamond mines to nuclear waste dumps, here are seven more underground wonders of the world.

Each of the five projects listed here took their toll financially and were paid for in part with human lives.

From tree furniture designs to unchecked acts of nature here are 25 examples of the amazing malleability of trees.

Here are five of these remarkable architectural designs for sustainable (and stylish) urban farm towers that may revolutionize agriculture as we know it.

These urban furniture designers prove recycling can be a lot more interesting than stuffing cans, bottles and cardboard into the proper containers.

Who hasn't imagined living on their very own floating paradise?

Despite having this essential factor in common the ultimate built outcomes range significantly in style, execution, materiality and purpose.

Believe it or not, there are a number of structures taller even than the infamous Burj Dubai.

This collection spans the extremes of design and brute-force ingenuity: from the obscenely luxurious to the absurdly simple.