15 most expensive mansions in the world – Queen Elizabeth lives in the most expensive house ever built (With Pics)

9. Xanadu 2.0, Seattle, Washington ($120.5M)

This high-end home equipped with advanced technology is owned by the richest man in the world Bill Gates. This massive cabin was constructed over a span of 7 years. It has amenities such as a 2,500 square-foot gym and a 60-foot indoor swimming pool.