The world’s largest building is located in Chengdu, China and recently displaced Dubai airport from atop the #1 spot:
The New Century Global Center, which recently opened in Chendgu, China, is 328 feet high, 1,640 feet long, and 1,312 feet wide. That’s roughly 20 times the size of Sydney’s legendary Opera House, four times the size of Vatican City, and three times the size of the Pentagon. And its 420 acres in floor space is nearly the size of the entire country of Monaco (499 acres).
For more photos of this monstrosity, check out this link.
Not to be outdone in the height department: China is currently building the world’s tallest building.