The ancient archaeological site of Tiahuanaco is located in Bolivia, in the department of La Paz, on the high plateau Altiplano, 20 km southeast of Lake Titicaca. The city of Tiahuanaco was the center of the civilization of the same name that existed on the shores of Lake Titicaca, which flourished in the 15th-12th centuries BC. Tiahuanaco is still a mystery, shrouded in myths and legends, scientists from around the world are trying to answer questions - how, when and by whom it was built. One of the grandiose structures of ancient Tiahuanaco is the Gate of the Sun (Inti Punku), located in the northwestern corner of Kalasasaya. The gates of the Sun are cut down from a giant rock monolith weighing more than 10 tons. Their height is 3 meters, width is almost 4 meters. Even in ancient times, these gates were smashed, restored and re-installed vertically, but where they were originally and how they were moved is not known. A bas-relief is carved on the frieze above the entrance opening, in the center of which there is a human figure clutching a staff in his hands, the head of the deity is decorated with the heads of a condor and a cougar, tears flow from his eyes, which is why he was called the “Crying God”. On both sides of the image are 48 figures of winged people - 24 on each side. Several bas-relief figures remained incomplete, as if the carvers had suddenly interrupted their work. According to scientists at the Gates of the Sun, a calendar is shown whose cycle was 287 days, which does not correspond to the cycle of planet Earth. Even the year of Venus, which was identified with the supreme god Viracocha, is 225 days. Many hypotheses, assumptions and scientific works are devoted to Tiauanaco and directly to the Gates of the Sun. However, there is no theory, at least approximately explaining the origin of the ancient city and its structures. Visitors to the ruins of this mysterious place still have to believe the Incan legends, which say that the city was built by mighty giants who, for some unknown reason, suddenly left it.