$100 million listing comes with owner

Forbes’ annual list of America’s most expensive homes identifies more than 30 properties priced at $60 million and up — including a 47-acre estate halfway between San Francisco and Silicon Valley whose owner, Christian de Guigne IV, has placed a special condition on the sale: De Guigne, 75, wants to continue to live in the 16,000-square-foot mansion until he dies. Asking price: $100 million. Source: forbes.com.