Utroba Cave, Bulgaria, a Thracian shrine carved around the 9th or 10th century BCE, ...

... depicts the vagina of the Goddess. There are other caves shaped this way in Bulgaria, but none are so spectacular. At 22 meters deep is an altar, possibly representing the cervix or the uterus of the goddess. At noon, light enters the cave from an opening in the ceiling, projecting the image of a phallus on the ground. When the sun is at the right angle, in February or March, the phallus stretches out to reach the altar (or cervix), symbolically fertilizing the uterus of the goddess before the spring sowing.

by kashkaval-tourist