Editor’s note: Sign up for Unlocking the World, CNN Travel’s weekly newsletter . Get news about destinations, plus the latest in aviation, food and drink, and where to stay. Tassili n’Ajjer National Park, Algeria CNN  —  “Labès?” (‘OK?”) asks Baba Atanof as a tourist struggles to get her leg over a large rock on a steep ascent in the Algerian Sahara Desert. Fighting jelly legs and vertigo, she can barely answer. This desert makes up 83% of Africa’s largest country. It’s the focus of a