Freeway with no speed limit in Germany

On a work trip to Germany, me and my colleague drove on that german freeway where there is no speed limit, must say it was an experience, my colleague was driving and she, yes SHE was doing around 180 km/h, crapping myself!
Anyone ever experienced driving on this freeway?

A number of German freeways are like this IIRC. Known as autobahns.

However, the most famous is the Nurburring (spelling adrift here) - and I think it is part of the F1 circuit.

Autobahns are awesome! They don't have speed limit, but near the cities however, there are small sectors which do. But anyways, driving a Porsche on the highway with 300+ km/h is still nice.