Well, If you were to give me a billion bucks right now, this is what I would buy.
A beautiful modern architecture home on the cliffs of a private island. Windmills for power, because I'm an eco-maniac.
It is not NEARLY done at all, as a matter of fact, I have several more things planned for it, such as a small nuclear reactor on the other side of the island, because I am very pro-nuclear power. I also might add a few underground and underwater structures, but this is about 3 or 4 hours' work, and I'm pleased with this foundation of the private island of my dreams. :D Hope you all like it!