Recent reports indicate that Tesla has purchased an additional 1,200 acres next to the current Gigafactory site already under construction and may look to buy another 350 more acres.
Tesla's Gigafactory was originally planned to consist of four modular "blocks," but now the company is planning to build seven modular blocks which will bring the Gigafactory's total size up to 24 million square feet.
While Tesla Motors has not confirmed the reports, if they are true that would make the Gigafactory the world's largest building in terms of footprint.
(more on Tesla's plans to expand construction of its Gigafactory...)