The Almendres Cromlech near Évora in Portugal is an 8,000-year-old stone circle, the biggest in the Iberian Peninsula. The site is on an east-facing hill. From there, only one mountain gap is visible, and during the equinoxes, the sun sets directly in that gap. There’s also a menhir at the hilltop that has a notch in which the spring equinox sunrise can be seen.