An ancient stone structure is located 40 km north of Dublin. It is older than the Egyptian pyramids by 700 years. According to legend, Newgrange is the home of the Celtic god of wisdom and the sun, Dagda. According to archaeologists, this place served as a tomb. There is also a version that this is one of the first observatories: during the winter solstice, the morning rays of the sun penetrate the hole above the entrance and illuminate the room from the inside. But researchers still have more questions than answers: where did they come from and what do the inscriptions on the stones mean, how did the builders achieve such accuracy, what tools did they use?