What is the world's largest building in terms of floor area?

New Century Global Center is a multipurpose building opened in 2013 in the Tianfu New Area of Chengdu, China. It has 1,700,000 m2 of floor space with 400,000 of it devoted to shopping. It also houses offices, conference rooms, a university complex, two commercial centres, hotels, an IMAX cinema, a "Mediterranean village", a pirate ship, skating rink and the "Paradise Island Water Park".