This undated photo provided by Christie’s International Real Estate shows an exterior view of Walnut Place, a $100 million estate on the market in Dallas. Rather than settle for garages of antique cars or a museum’s worth of paintings, billionaires are increasingly willing to pay $100 million for homes that can serve as showcases for their fortunes, according to an analysis issued Thursday, April 30, 2015, by Christie’s International Real Estate. (Stephen Reed Photography via CIRE via AP) MANDATORY CREDIT ORG XMIT: NYBZ203