A bird's-eye view offers magnificent views of San Luis Potosí. However, the most unusual place that should not be missed is the famous Cave of Swallows. People have known about its existence since ancient times. But the first studies which opened it up to the public were carried out only in 1966.

This karst cave with a diameter of 50 meters and a depth of 512 meters is the second largest in Mexico. The vertical descent to its main bottom is 376 meters. It is considered the longest in the world. That attracts thousands of climbers to these places every year. The descent to the cave with all the equipment takes only a few minutes. Unfortunately, you will not be able to get up so quickly. Even experienced climbers need about two hours to climb due to difficult and dangerous obstacles as well as its inhabitants. The cave is home to several species of venomous snakes. Therefore it is necessary to take precautions and keep a close eye on everything that you can encounter along the way. There is everything that daredevils need: a special platform is well equipped for attaching climbing equipment. But you can only go down at a certain time so as not to disturb its inhabitants. Besides, the state authorities allowed only one side equipped with anchors to descend. For fans of extreme tourism, there are experienced guides who conduct interesting excursions through the inner tunnels of the cave. After the rainy season, nature creates a wonderful sight there: hundreds of thin streams flow down its walls, forming cascading waterfalls and small lagoons.

Fans of less active recreation will also be amazed. The cave contains the nests of more than 2 million birds. They leave it in search of food at dawn. And they return to their nests at sunset. An unforgettable sight can be seen at this time: giant flocks of birds with a wild cry and high speed dive deep into the cave to their nests, where the chicks are eagerly waiting for them.