Beijing Airport cost 27 billion yuan to build in less than 4 years using a workforce of 50,000 people. The floor area covers 1.3 million square meters in a building over 4 km long, making it the world's largest. It features an automated people mover that travels at 80 kph, 84 shops, over 100 restaurants, and a curved roof with skylights oriented to maximize early morning sunlight to reduce energy costs for heating with a golden tint evoking the Forbidden City.