The Mercedes and Porsche museums
Even in 2005, before the new 'Mercedes World' had been built, the Mercedes Museum right next to the stadium was well worth a visit.  It has dozens of old and new cars on display, is free to get in and provides visitors with free audio guides in English, German, French, Spanish, Japanese, Chinese, Italian and Russian.  Opening hours in 2005 were: Tuesday to Sunday, 9am to 7pm.  More information is available on the Mercedes Benz website.  There's a photo of the 'Mercedes World' building under construction, showing its proximity to the football ground on our stadium gallery page.

The photos below show just some of the cars on display.  Click on any image for a larger picture.