Calakmul

Declared in 1989, it is the largest tropical forest reserve in Mexico and part of the great Maya Forest, the second largest block of continuous rainforest in the Americas after Amazonia. Hidden inside it are the ruins of Calakmul, one of the most powerful city-states of the Classic Maya period and a historic rival of Tikal, with over 6,000 structures identified and one of the largest Maya pyramids known. Since 2014 the reserve and the archaeological zone have shared a mixed UNESCO World Heritage listing — natural and cultural at once — recognising both its biodiversity and the legacy of the Maya civilisation that managed this forest sustainably for more than a thousand years.