The Message on the Guidestones

The guidestones had astronomical features. The explanatory granite slab on the ground near the guide stones explained them. There is a horizontal slot in the central pillar that corresponds to the annual movement of the sun, allowing you to determine the date of the ring equinox and autumnal equinox. Third, there's a channel through the capstone that lets you determine midday or noon, or 12 p m, throughout the year.