Since aircraft have been mapping the countryside of England in the last 60 years, over 15 cursuses have been identified there from the air, all thousands of feet long, although the entire population of Britain is thought to have been only a few hundred thousand at the time they were constructed. To show how world wide this ancient 'prehistoric' civilization was, here's another cursus complete with bank and ditch on each side. There are 26 long mounds with ditches beside them stretching for 2 miles in yellowish-red sandy/gravelly subsoil:

That's an artist's impression of the effect,(showing only 20 mounds) with the largest US fleet Carrier to scale. But here's a colour representation of a cross-section, to illustrate how it was constructed:

There are gaps between these constructions each side, just as for the cursus in England. But the 'Poike" ditch, so called, happens to be about 8,600 miles away from the Dorset cursus. It's on Easter island, the most remote island on earth, famous for its tall megalithic statues. The Poike cursus too, can only be seen properly from the air. The explanation of a racetrack won't do for this cursus, there were no horses or other animals suitable for racing on the island before Europeans arrived about 300 years ago.

The effect seen from the air soon after construction must have been remarkable. At the Dorset cursus: two gleaming white parallel lines, miles long with grassland between them and forest outside the area; at the Easter island cursus, two yellowish-red parallel lines miles long, from coast to coast of the island which would certainly identify it from a mile or so up in the air.