When most of us think of Tesla Motors, we think of the US$100,000 all-electric Roadster. The fact is, though, the first time that most of us ever see a Tesla in real life, it will probably be the less expensive, five door Model S sedan. While the company has sold over 1,300 Roadsters worldwide, the Model S has yet to start production. When it does, however, it will be in the new Tesla Factory, unveiled this Wednesday in Fremont, California. It is the state’s only auto assembly plant and the world’s first facility dedicated exclusively to the mass production of electric vehicles.

The factory is located in the former New United Motor Manufacturing, Inc. (NUMMI) building. NUMMI was originally run as a joint venture by Toyota and GM, where vehicles that were sold under both brand names had been manufactured since 1984. Toyota will be now be collaborating with Tesla in that same building, on production of the electric version of Toyota’s RAV 4 and other projects.

Fremont is in the Silicon Valley region, near Tesla’s Palo Alto headquarters, so the engineering know-how will be readily accessible. NUMMI was still being used to produce Toyotas as recently as this April, and Tesla claims it is “one of the largest, most advanced and cleanest automotive production plants in the world.” The plant utilized – and is still equipped for – the Toyota Production System, and is capable of producing half a million cars per year. According to a report in Autoblog, Tesla plans to produce 20,000 vehicles there annually – both the Model S, and future models.

The bodies for the company's Roadsters are currently made by Lotus in the UK, with powertrain production and final assembly taking place in California.

“This is a momentous day in Tesla history, turning our advanced electric vehicle technology into a mass manufacturing reality,” said Tesla CEO Elon Musk. “Model S is blazing a new trail for the industry and it will all happen right here – the Tesla Factory gives us plenty of room to grow.”