Nordschleife translates into English as ‘Northen Loop’. It is the Nordschleife that is open to the public and the 20km+ track is widely acknowledged as the toughest in the world. It was originally built as a test track for the growing German car industry, construction started in 1923 and the track was completed, and opened, in 1927.
There doesn’t appear to be a definitive number of corners as there are different ways to count them. Some counts are around 73, others proclaim over 140. Either way, there are a lot! This map shows the names and location of the major corners on the track. You can click the image for a larger version the map, although this still does not give a full indication of the severity of some of the corners. For example, on this map Adenauer-Forst looks like a gentle curve. In reality, it is a steep climb to a series of corners, culminating with a very tight left-right chicane. Being a blind turn, this chicane tends to catch out a lot of inexperienced drivers as the approach speed is reasonably fast.
Still, this map is a great reference and is worth keeping on file (click on the image to load a larger version – 1600 x 1180px).
This photo of the course map was taken just near the ticket booth where you purchase your tickets to lap the ‘Ring. The Touristenfahrten entry is at Tiergarten and the course direction is clockwise. Unless at the track for a closed session it is not possible to lap on the current day Grand Prix circuit, which is the loop at the bottom of the map.
There was also a SÃ¼dschleife, or Southern Loop, and while parts of the old track are still possible to find, it has essentially been lost forever. (Sounds like a research assignment and new post topic I think!)