Alpe d'Huez - 1838m
Probably the most famous climb in cycling.  21 hairpin switchbacks over 13km.   There are some 12% sections on the first two switchbacks, but it levels out somewhat as you ride up. 

Here's the middle sections

99 TDF Alpe d'huez 1999 Tour de France Photos

99 TDF Alpe d'huez 2003 Tour de France Photos

99 TDF Alpe d'huez Profile 1

99 TDF Alpe d'huez Profile 2


Photo of the Alp

Aerial view from the 2004 Tour de France