If you’re a heavy user of Facebook, Messenger, or Instagram, you’d probably never guess that on the first floor of a building at the social networking giant’s Silicon Valley campus, behind a key-card access door that grants entry only to a select few people, is a scanning electron microscope .

This is the kind of high-end device you might find in a university science lab, or maybe in an R&D facility of a company doing complex scientific research. But Facebook?

Absolutely. The microscope is one of a group of very expensive, precision machines that are part of Area 404, Facebook’s brand-new hardware lab, 22,000 square feet of pristine space under bright lights dedicated to helping the company design, prototype, test, and even build hardware for projects as diverse as its Aquila Internet connectivity drones, Oculus VR, its data centers, and other systems.

The lab’s scanning electron microscope, an expensive device used in failure analysis. Photos: Daniel Terdiman for Fast Company

Facebook has long had a hardware lab, but years ago, the facility was little more than the size of a desk in an old mail room at the company’s first offices in nearby Palo Alto. This is an entirely different animal.

The idea behind the lab, Facebook’s head of engineering and infrastructure Jay Parikh told a group of reporters yesterday during a tour, was to provide engineers from a wide variety of the the company’s teams a place to come together to share expertise, and work quickly on projects. Plus, why waste weeks or even months and lots of money sending designs to third parties to prototype or stress-test something when, said Parikh, engineers “are able to take that stuff, walk it down the the end of the hallway and see what’s happening?”

Facebook isn’t saying how much it has invested in the new lab, but given that it has the kind of machinery that surely costs six figures or more, you can bet that the number is in the many millions of dollars.

Among the machines you can find in the lab are a 9-axis mill-turn lathe, a 5-axis vertical milling machine, a 5-axis water jet, a sheet metal shear and a sheet metal folder, a CNC fabric cutter, a coordinate measuring machine, a CT scanner, and of course, the scanning electron microscope.