Somewhere between Atar and Chinguetti in Mauritania the road passes through a very impressive gorge with rocky escarpments on either side. Believe it or not, as one of the only points at which vehicles can get between the plateau and the lower lands to the East, this road has a police checkpoint - even though there must only be around 10 vehicles passing each day!

(This picture is shown with the kind permission of Roraigh Ainslie)