Inside Facebook's robotic inner sanctum: a tour of its highly secretive hardware lab

Facebook wants the world to know it's serious about hardware, but just how much is it willing to reveal?

It's an uncharacteristically gloomy day at Building 17 of Facebook's Menlo Park headquarters. From the outside, it looks like any other office; it's unremarkable except for the free valet parking booth erected in front of the lobby, a perk that saves staff from having to walk more than a few steps from their cars.

The drab facade belies the state-of-the-art 22,000-square-foot hardware lab inside, where Facebook will prototype its solar-powered drones, internet-beaming lasers, Oculus VR headsets and custom servers.