The Gruta del Palacio (“Palace Cave”) is an ancient rock formation located in Central Uruguay, near the small town of Trinidad.

This wonderful geological feature is composed of sandstone and sedimentary rock. The natural wonder formed around 70 million years ago during the Late Cretaceous period, later solidifying into its current appearance during the Paleocene.

The peculiar cave is formed by an upper shell of sandstone sustained by multiple 6.5 feet (2-meters) tall natural columns that create a structure that resembles the porticoes of palaces, hence the name. These features create a large labyrinth of caves, of which only a small portion is accessible to the public.

It has been suggested that the caves could have been inhabited by the indigenous population of the region during prehistoric times. Some local legends are linked to this rock formation, but no definitive proof of ancient human presence has been found.

First studied in 1877, the caves were explored during the 20th-century, and in 2013, the site became the first geopark in Uruguay and the second in all of South America. It is now being considered for possible inclusion onto the list of UNESCO World Heritage sites.