If it's built out to the full size in the original plans, the Tesla gigafactory outside Reno, Nevada, will cover 10 million square feet.
That's the equivalent of more than 260 U.S. football fields, which would make it one of the largest buildings in the world.
Yesterday, Tesla Motors CEO Elon Musk officially opened the gigafactory building, which today is 14 percent of that size on a 3,000-acre site.
Owners of Tesla electric cars have been invited to an event to be held at the plant on Friday, but Musk spoke to the press yesterday from the site and declared it officially open.
The factory's main mission is to produce lithium-ion cells at a far lower cost than any today, which will make the battery cost of the company's upcoming Model 3 sedan low enough for a starting price of $35,000.
The Tesla Model 3 is supposed to go into production just 12 to 18 months from now, and ensuring the supply of cells and battery packs in sufficient volumes is what made the huge building necessary in the first place.
The ultimate cost of the site could be as high as $5 billion, though Panasonic—which will fabricate the cells—and other partners are expected to contribute part of that cost.
The Associated Press notes that Panasonic's share of the total will be $1.6 billion. The company expects to begin production of cells before the end of this year.
Tesla moved up its plans for high-volume production of the Model 3 after it received more than 350,000 deposits of $1,000 each for the car in late March and early April.
The company's ability to get the Model 3 into volume production remains one of its greatest challenges.
The launch of its previous product, the Model X electric luxury crossover utility, was plagued with delays and glitches, many of them due to its innovative but hard-to-engineer "falcon doors."
Musk said earlier this year that Tesla plans to have sold half a million Model 3 cars a year by the end of 2018.