The Palace Cave, Gruta del Palacio in Spain, a 70-130 million-year-old archeological site from the Cretaceous period, is situated at the 235th km on Route 14 (running from Trinidad, capital city of Department of Flores to Mercedes, capital city of Department of Soriano, W Montevideo). It was first thought to be artificial, a work of the aborigines of the region. In 1877, Genoese Speleologist Mario Isola explored the cave, and penetrated about 150 metres into it. Ancient chronicles state that it was possible to enter on horseback to where today it is hardly impossible to penetrate even on foot. More recent surveys have determined that the cave is more than 400 meters long, out of which only 40 are of easy access. The action of natural sedimentation and agricultural activities has been the cause of collapses, and formation of new soil layers, that have partially filled the cave. At present one can advance on foot only 8 meters in depth, and forward, through a 50-70 centimeter hole, 30 meters deeper. From there on, it is necessary to remove sediments and stones to clear the passage, which experts are at present set to do. The rare sandstone columns are 30 to 100 centimeters in diameter.

This site has quite odd characteristics. Although there is no evident air current, all the system is well ventilated. In winter, temperature rises to 20 C degrees inside the cave, and the water in the permanent deep pools is 8 C degrees lower than the temperature outside. A rare species of sprawns among other unique fauna species found in the cave - live in these pools' waters. Beyond the labyrinthine formation of the entrance, scientists have discovered the head of an underground pool.

As soon as the conditioning works are finished, the Town Hall of the Department of Flores plans to rule the visits into the by then duly signposted - cave and to complement them by the visit to a small museum and guided tours.