Start absurdly early. Much of what is now Brazil lay under an inland sea, and when the water finally withdrew it left behind massifs of limestone — the compacted remains of everything that had lived and died in that sea. One of those massifs stood directly across the path of the Peruaçu River, a tributary running down toward the São Francisco. Limestone is soluble, and a river with nowhere else to go is patient. The Peruaçu dissolved its way through, then kept working the fractures on either side, until the block of rock became a honeycomb. Around 140 caves have been catalogued inside the park, and the river still crosses the park from northwest to southeast before delivering itself to the São Francisco. Speleologists keep finding grottoes nobody has documented.

The rock art here dates from the tenth millennium BCE, which is to say the painters were at work while the last ice age was still letting go of the planet. Figures cover the walls of Janelão and other caves in the system — bold, high-contrast, deliberately placed. More than eighty archaeological sites have been recorded across the canyon. It is worth sitting with the arithmetic for a second: the oldest paintings in the Peruaçu predate the earliest Egyptian dynasties by more than six thousand years, and were already ancient when the first stone went into Stonehenge. Nobody built a monument here. They used the rooms the river had already made, and they came back to them, generation after generation, for longer than any civilisation has managed to last.

One cave in particular has shaped how archaeologists read the canyon. Lapa do Boquete, in the municipality of Januária, served as a burial ground from roughly four thousand to one thousand years ago, and the funerary practice recorded there was anything but simple — multiple burials in the same ground, the deliberate handling and rearrangement of bones, stone structures, ceramics and worked stone left alongside. Walter A. Neves and Renato Kipnis are among the researchers who worked the site and published on its mortuary customs and the diets of the people buried there. Strip away the technical language and what remains is a community that carried its dead into a specific cave for three thousand years, and did something careful with them once they were inside.

Above ground the park straddles a border between biomes. Cerrado, the Brazilian savanna, meets caatinga, the thorn scrub of the northeast, and the transition produces seasonal deciduous and semi-deciduous forest that drops its leaves and waits. Average temperature sits around 18°C; annual rainfall stays under 1,200 millimetres and arrives mostly in summer. Maned wolves, cougars, jaguars and ocelots all range through the protected area. In the water there is something odder: Trichomycterus itacarambiensis, a small catfish adapted to life inside these caves and found nowhere else on Earth. It is a useful reminder that the karst is not merely scenery — it is a set of enclosed worlds, each one running its own long experiment.

The park spans Januária, Itacarambi and São João das Missões, and the Xakriabá people have a documented presence in this landscape — a continuity with the canyon that no visitor route can replicate. ICMBio, Brazil's federal conservation agency, has administered the park since its creation on 21 September 1999, and access is deliberately rationed: six visitor routes reaching eight caves, guided, on a schedule. The restrictions exist because speleothems — the stalactites, stalagmites and flowstone that took millions of years to accumulate — break in a second and do not grow back on any human timescale. In 2025 UNESCO inscribed the park on the World Heritage List under criteria vii and viii, for natural beauty and for the record the rock keeps. The rock art, older than the listing by a hundred centuries, was doing that already.