A long climb. Do not slack off in the red bits. You must stand and fight. (Well, I have to stand and fight - a stronger cyclist might breeze up, casually smoking a Gitane. Sadly in the 1967 Tour de France Tom Simpson breezed up, buzzing on amphetamines and alcohol, and conked out)
Shorter, more famous, and perhaps more picturesque than Ventoux. Apart from the first bend it's easy - unless, that is, you want to do it quickly.