The escarpment above Kaapsehoop is a strange place even before you get to the stones. The village itself is a scatter of tin-roofed cottages in a field of weathered sandstone boulders, with wild horses wandering the street and mist most mornings. Walk east along the edge and the ground falls away two thousand feet to the lowveld. On a level shelf near that edge, in the long grass, stand two upright slabs of dolerite taller than a person, with a rough ring of lower stones around them.

In 2003 a pilot named Johan Heine, flying the escarpment, looked down and saw the ring from above and thought it looked deliberate. He went back on foot, took bearings, and became convinced that the two tall stones lined up on the cardinal points and that other stones marked the solstices and the equinoxes. He brought in Michael Tellinger, a writer with an interest in ancient mysteries, and between them they gave the place a name: Adam’s Calendar.

The claim they built on it grew quickly. By working the precession of the equinoxes backwards from where Orion’s belt would have risen in line with the stones, Tellinger argued the calendar had been set out at least seventy-five thousand years ago, which would make it the oldest built structure on earth by a very wide margin. In later books and talks that became two hundred thousand years, then three hundred thousand. The builders, in this telling, were a lost civilisation mining gold for visitors from elsewhere, and the thousands of stone circles scattered across the Mpumalanga highveld were their energy machines. Tellinger has lectured on it around the world, and tour operators bring visitors to the stones at sunrise.

The archaeologists were not asked and have answered anyway. The ring is one small piece of the largest stone-walled landscape in southern Africa, the settlements of the Bokoni people, who farmed the escarpment from about the sixteenth century until the wars of the early nineteenth scattered them. Their homesteads, cattle enclosures and terraces run for a hundred and fifty kilometres along the mountains, tens of thousands of structures, most of them never excavated. The Kaapsehoop ring, on this reading, is a kraal, or part of one, and the tall stones are either natural or set up for reasons nobody has recorded. The alignments, they add, are the sort you can find in almost any scatter of rocks if you are looking for them. Nobody has dated the stones themselves, because you cannot date a rock to when it was moved.

What is odd, and worth saying, is that the argument has done the Bokoni a favour. Before Adam’s Calendar hardly anyone outside a university department had heard of them. Now people drive to Kaapsehoop to see the oldest structure on earth and go home having learnt that a farming civilisation built terraces along the escarpment for three centuries and left almost no trace in the history books. It is a strange road to a real history, but it is a road.

The stones stand where they stood. On a clear morning the sun comes up over the lowveld between the two tall ones, or near enough, and the mist rolls in over the ring by nine. Whoever put them there had a good eye for a view.