The M1 southbound from J18 to J8
I joke, I joke...
It's not the entire road, but a very small section. The B3081 southbound, just outside my hometown of Shaftesbury. Precisely, the very small section known as 'Zig Zag Hill' - apparently the bendiest road in Britain. The section just after the top of hill affords stunning views, and a couple of good, fast corners.
Here is the Google Maps link.
It's such a blast to, well, blast up it. Especially on a summer's afternoon (I've heard they're nice, apparently
).