Moray
From Chinchero, the road drops toward Moray, where the Incas cut a series of concentric circular terraces into a natural depression in the earth. The going theory is agricultural: each terrace ring sits at a slightly different elevation and receives different sun exposure, creating a range of microclimates within a space a few hundred meters across — in effect, a laboratory for testing which crops would grow where across the empire's wildly varied terrain. No one is entirely certain that's what it was for, but the theory has stuck for a reason: it's hard to look at the precision of the terracing and not see a system built for measurement.