Petén Basin, Archaeological site in Petén, Guatemala.

The Petén Basin is an archaeological site in the Petén region of northern Guatemala, covering a broad expanse of tropical rainforest. The landscape shifts between flat jungle and raised hills where the remains of ancient settlements can be found.

Settlements in the basin date from the second millennium BCE, with Cuello in Belize occupied from around 1200 BCE and maize cultivated by about 2800 BCE. El Mirador built causeways and structures 40 to 72 metres high before many centres were abandoned between 150 and 250 CE. The Classic period (c. 200–900 CE) saw Tikal and Calakmul flourish; the population fell by two-thirds between the mid 9th and mid 10th centuries.

The basin gave its name to the Petén architectural style, spread to other Maya regions, and to glyph-covered stelae whose decipherment rebuilt Classic-period history. The name Petén derives from the Itza word for island, applied to Tayasal in Lake Petén Itza. Visitors still see carved stelae at Tikal, Yaxhá and Naranjo.

Most visitors travel first to Flores, which serves as a starting point for excursions into the surrounding areas. From there, roads and trails lead to different ruin sites, with some only reachable by guides or longer hikes.

Below the dense canopy, many structures remain hidden that have been revealed through modern laser technology from the air. These discoveries show that the settlement was far denser than previously thought.