As far as cobblestoned mountains go, probably the most well known is the old road up the south side of the Gotthard Pass outside Airolo in Switzerland. The Val Tremola, as it is known, is about a 1000m climb (1100m to 2100m). The grade is mostly 7-8% as I recall. They went up it in the the Tour of Switzerland or some such race a few years back.
http://www.climbbybike.com/profile.asp?Climbprofile=Passo-del-San-Gottardo&MountainID=5504
http://www.climbbybike.com/profile.asp?Climbprofile=Passo-del-San-Gottardo&MountainID=5504