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?