British starchitect Lord Norman Foster has bought a second unit at white-glove co-op 912 Fifth Avenue, bringing the amount of his total purchases in the building to $13.9 million. According to city documents, the Pritzker Prize winner and his wife, Lady Elena Foster, closed on unit 8B June 29 for $6.7 million, just two months after purchasing unit 8A for $7.2 million. The couple plans to combine the units into one large floor-through apartment in the luxe pre-war building, which is located between 72nd and 73rd streets, said a source. The seller is listed as Barbara T. Missett. Foster, who designed the triangular-framed Hearst Tower at 300 West 57th Street, is working on 200 Greenwich Street, a 78-story office tower at the World Trade Center site, and Masdar City, a zero-waste, car-free five-square-mile city in Abu Dhabi. [more]