Assekrem is a plateau at 2,726 metres in the Hoggar mountains of southern Algeria, and a hermit built a stone house on top of it in 1911 for the view. People still come up for the same thing. The east-facing rim is where everyone takes position before dawn, and the light needs a full twenty minutes to work across the field of spires. Then you turn round. The Atakor runs in every direction, hundreds of black volcanic necks worn out of the desert, with nothing beside them to give you a scale. Tahat, the highest mountain in Algeria, is one of them.
Charles de Foucauld's retreat is dry stone and still standing. The Little Brothers of Jesus keep it, and open it to anyone who has walked the last kilometre from the road. Inside there is very little: bare rooms, and windows onto the same view you climbed for. It is a working religious house rather than a museum, and it is kept that way. Beside it stands a hut that is not an ordinary weather station. So little traffic or industry lies upwind that the air arriving here counts as background: this is one of about thirty places on Earth trusted to say what the atmosphere is like with human pollution left out. Tamanrasset, the nearest town, is eighty kilometres off and hidden below the horizon, so after dusk the sky fills without competition, and the air up here is thin and dry as well. Most people drive up for the morning, but the Atakor is walked too, several days between volcanic domes and Tuareg camps with camels carrying the loads, this summit saved for your last morning. De Foucauld spent eleven years here and made almost no converts. What he did instead was write the Tuareg language down: four volumes of dictionary and poetry, published thirty-five years after his death and still the record of how Tamahaq was spoken in the Hoggar.