London's biggest mall opened despite the gloomy economic climate that threatens to dampen vital Christmas sales. London mayor Boris Johnson helped open the Westfield London mall , which cost 1.6 billion pounds ($2.5 million), including a large chunk spent on new rail stations and bus connections.With some 300 shops, 50 restaurants, and many deluxe amenities, its operators bill the mall, the Australia-based Westfield Group, as one of the largest in the world. The Westfield Group projects that 21 million people will shop in the mall each year.