Bill Gates's house is a large mansion in the side of a hill which overlooks Lake Washington in Medina, Washington, United States of America. The 66,000-square-foot (6,100 m) mansion is noted for its design and the technology it incorporates. It is nicknamed Xanadu 2.0[1] after the title character's estate in Citizen Kane. It took 7 years to build and cost $63 million.