The Lead Hills
I hunted out the hilliest road I could find, as part of my Lands End to John O'Groats training. This is the road up the Lead Hills in Ayrshire towards Wanlockhead. The aesthetically pleasing curves in the photo don't show the >400m of ascent in 7 miles. This is about as severe a climb as I'll encounter en route I think (although there's many such climbs).