A billion dollar yacht.
Ladies and gentlemen of a far different tax bracket than my own, may I introduce the Streets of Monaco?
Sure, it's still just a design waiting to be built, but prepare yourself for a new level of opulence, emulating the streets of Monaco (which I'm sure you've been to, since you're rich).
On the top deck, there will be scaled-down versions of uber famous Monaco landmarks like the Hotel de Paris, Monte Carlo Casino, Café de Paris, Loews Hotel, and La Rascasse. The real pinchers are a fully-functional go-kart circuit track based on the Monaco Grand Prix race track, complete with a tunnel complex, and the submarine and helipad.
And not to mention, the standard multiple swimming pools, swim-in Jacuzzi bar, multi-use sports court for tennis and basketball, dance hall, spa and hair salon, and accommodations for 16 guests and 70 staff members. The main apartment for the yacht owner is spread over three floors and covers 4,800 sq. ft.