Mexican telecommunications mogul Carlos Slim, who beat out Warren Buffet and Bill Gates to capture the title of World's Richest Man earlier this year with an astonishing net worth of $53.5 billion, has purchased the stunning Duke-Semans Mansion in New York for a cool $44 million. As we reported back in January, cab driver-turned-fertilizer king Tamir Sapir had listed the palatial townhouse, said to be the only private mansion left on Fifth Avenue, for $50 million. According to the Wall St. Journal, Slim cut the deal to snag it for $6 million less with Sapir directly. Sapir bought the historic seven-story Beaux Arts mansion located across from the Metropolitan Museum of Art from relatives of Doris Duke for $40 million in 2006. The 20,000-square-foot mansion, built in 1901, currently has a doctor's office in the basement, a five-story main residence, a penthouse duplex on top, 12 bedrooms, 14 bathrooms, and 11 wood-burning fireplaces.