As the History Channel explains, the stones are aligned to precisely track astrological and solar cycles.

“The east and west corners of the monument track sunrise and sunset. A slot that’s cut into one of the slabs marks the winter and summer solstices. A shaft that’s drilled through the center of the stone marks Polaris, the north star. And a slit that’s cut through the capstone marks the perfect noon time. So that means it’s this sort of granite Swiss Army knife: The Guidestones have a calendar, a compass, a translator and a guide…which is bananas.”