The Kalser Glocknerstrasse up to the Lucknerhaus (which is the basecamp for all those you want to climb the Großglockner - highest mountain in Austria at 3798m). The Lucknerhaus is at 1920m and you will reach it after 5km flat and 20km uphill. It is tough climb which was used in the Tour of Austria in the 80's. Beautiful high alpine views during the climb guaranteed.