It is the name given to a megalithic monument that is located in Sardinia. Towers made with stones and that are supported by their own weight. They had a religious character and a great architectural precision, which allows to observe certain celestial phenomena. There are more than 8 . 000 on the island of Sardinia. Among others, they have the property of reflecting the exact moment when the moon is in the center of the celestial vault. This event occurs only every 18, 5 years.
