For those of you in the UK or visiting, try the Wynatts Pass in the Lake
District, Cumbria, England.
It is very scenic, and also the scariest drive I have ever made.
The road is very narrow (room for only one vehicle) and winds its way
through the mountains. Because of an optical illustion provided by the
surrounding mountains you are never quite sure whether you are going
uphill or downhill.

http://www.cumbria-the-lake-district.co.uk/