The word extreme means different things to different people, and to these homeowners it means pushing the envelope as far as possible. From construction to completion, take an up-close look at some of the world's most spectacular houses ever built - from a cliffside home perched on top of a waterfall to one that is built out of cargo containers, from a home in the middle of a Brazilian rain forest to one that looks like a whale - and find out what makes them all so unique.