pitch blackness. Opening out from these subterranean corridors are dozens of rock-hewn side chambers, some large enough for half a dozen people, others seemingly for solitary confinement. There are niches hacked in some of the chamber walls which might have housed oil lamps, and lintels which extrude like hammock pegs. Running through the bewildering network of tunnels and chambers are smaller shafts, some of them air vents, others water ducts which allowed the nearby spring to gush and echo through this elaborately constructed underworld.Right in the heart of the labyrinth is a stela carved in the early Chavin style, a clawed, fanged and rolling-eyed humanoid form, boxed inside a cramped cruciform chamber which rises to the top of the pyramid. The loose arrangement of stones in the roof above, which form a plug at the crown of the pyramid, have led to speculation that they might have been removable, allowing the Lanzon, as the carved stela is known, to point up like a needle to a gap of exposed sky. Other fragments of evidence from the site, such as a large boulder with seven sunken pits in the configuration of the Pleiades, suggest that an element of the Chavin ritual - perhaps, given the narrow confines around the Lanzon, a priestly rather than a public one - might have involved aligning the stela with astronomical events.This plaza and pyramid was Chavins original structure, but over the centuries more and grander variants were added. There are several shafts, some still unexcavated, which lead down into larger underground complexes, their stonework more regular than the old pyramid and their side-chambers typically more spacious. There is a far larger sunken plaza, too, square rather than circular and leading up to a new pyramid and surrounding walls on a more massive scale. Whatever happened at Chavin, the architecture suggests that it carried on happening for centuries, and for an increasing volume of participants.The term most commonly applied to what went on at Chavin is cult, although elements of meaning might perhaps be imported from other terms like pilgrimage destination, sacred site, oracle or, in its classical sense, temple of mysteries. This is a conclusion partly drawn from lack of evidence that it represented an empire, or a state power: there are no military structures associated with it, nor centralised labour for major public works like irrigation or housing. During the several centuries of its existence, tribal networks would have risen and fallen around it, changes in the balance of power apparently leaving its source of authority untouched. Its cultic - or cultural - influence, though, spread far and wide. Throughout the first millennium BC, Chavinoid sites spread across large swathes of northern Peru, and pre-existing natural huacas began to develop Chavin-style flourishes: rock surfaces carved with snaky fangs and jaws, standing stones decorated with bug-eyed, fierce-toothed humanoid forms. People were clearly coming to Chavin from considerable distances, and carrying its influence back to far-flung valleys, mountains and coasts.Was Chavin, then, a religion? Theres been some speculation that the carvings on the site represent a Chavin cosmology,