Sani Pass is a gravel ladder of hairpins climbing the Drakensberg escarpment from South Africa into Lesotho, and the wall it climbs is not a mountainside. It is hundreds of lava flows stacked on top of each other, poured out as Gondwana began to tear apart. Up to 1,400 metres of that basalt still caps Lesotho, and the escarpment is its worn edge. That is why the Drakensberg ends in a wall rather than a slope. The last eight kilometres are the pass proper: blind hairpins on loose gravel, gaining 900 metres, each bend opening a wider view back down the valley. From the rim the whole thing unspools beneath you, hairpin after hairpin, with the lowlands hazy beyond and nothing fenced between the plateau grass and the drop.
On the upper bends the cliffs are worth scanning. This is one of the last strongholds of the bearded vulture, a bird that lives almost entirely on bone. It carries big ones aloft and drops them onto rock until they shatter, then swallows the splinters and the marrow inside. It is also the one place where a road gets you close to the Drakensberg rockjumper, siskin and mountain pipit, three birds that live along this escarpment and nowhere else. At the top, Sani Mountain Lodge keeps a wood fire burning at 2,874 metres and claims the highest pub in Africa, with tables facing straight over the edge. Beyond it the plateau opens, treeless grass to the horizon, herders wrapped in blankets that are national dress rather than bedding, each pattern marking where its wearer stands in life. By early afternoon the warm air that climbed the escarpment tips over the rim as cloud and fills the valley behind you. And the border itself, after all that climbing, is a whitewashed hut with a flag on a pole, standing alone on the grass, where a hand stamps your passport and the summer flowers grow up to the fence.