Timelapse of the night sky above the prehistoric Cromlech of the Almendres, near Evora, Portugal. This megalithic complex is the largest existing group of structured menhirs in the Iberian Peninsula, and is one of the largest in Europe. It dates back to the 6th millennium BC. The orientation of the stones suggests that it may have been used as an astronomical calendar. The clip ends with a close-up of the constellation Orion.