Yellow safety tape along the floor marks where its safe to walk, lest you get run over by all the guys driving carts presumably laden with car parts and information that nobody else will see for years.
Secure doors -- large enough to fit a full-scale vehicle through -- line the corridor, and plenty of designers are hard at work on the other side of them, working on vehicles that might eventually wind up in your garage. In the back, though, there's a metal door leading to a staircase that descends further into the Earth. It's certainly inconspicuous, and you'd be forgiven -- maybe even thanked? -- for thinking it's just a janitor's closet.
The hallway at the end of that staircase is where things become an amazing mix of creepy, foreign, and indescribably cool.