After more than two years of construction, the Tesla Gigafactory in Nevada started churning out electric car batteries in 2016, but judging by recent drone footage, it is far from completed.

Photographer Matthew Roberts sent a DJI Phantom 3 drone soaring above the huge facility, about 20 miles east of Reno. His footage reveals skeletons of buildings extending out from the already-completed parts of the factory, which started up some production lines for Tesla lithium ion batteries in July.

The drone video is starkly different from the official images depicted on Tesla's website, many of which were taken immediately after construction began and show little more than a massive hole in the ground. Tesla has been secretive about the facility; it briefly opened its doors to journalists in July, but local reporters who tried to get in in 2015 were arrested.

Tesla hopes the Gigafactory will achieve its full capacity by 2018. In addition to batteries, it will also churn out complete Tesla vehicles—500,000 of them per year. Production of that scale is crucial to the success of the company's forthcoming Model 3, a $35,000 car with 215 miles of range that Tesla CEO Elon Musk is positioning as an electric car for the masses.

For now, most of Tesla's manufacturing takes place at its Fremont, Calif., factory, a 5.3-million-square-foot facility formerly owned by General Motors that began making Model S vehicles in 2012.

The finished portions of the Gigafactory, by contrast, already cover 5.5 million square feet, and once the entire facility is completed, it will have the largest footprint of any building of the world, according to TechCrunch.