Meeting point of opposites
In most cultures it is a significant place of meeting with transcendent powers (gods, spirits, the dead). It is often close to the symbolic content of the door, since the crossroads can also symbolize the necessary transition to the new (from one phase of life to another; from life to death). To win the favor of the gods or spirits, obelisks, altars, or stones were erected, or inscriptions were placed at crossroads. Practically everywhere in Europe crossroads were also regarded as the meeting place of witches and evil demons. For this reason, Christians have erected at crossroads crosses, chapels, and statues of the Madonna and the saints. Among many African tribes the symbolism of the crossroads plays a significant role in ritual acts. In Greek mythology Oedipus slays his father at a crossroads. The Greeks made sacrifices to a goddess of the (three-way) fork in the road who was often represented in triple form: Hecate, goddess of ghosts and magic, who was also closely associated with the realm of the dead. The statue of Hermes, the psychopomp (spirit guide) stood guard at crossroads and forks in the road.
(Above is an excerpt from the entry for Crossroads in "The Herder Symbol Dictionary."
Translated by Boris Matthews. Chiron Publications, Wilmette, Illinois.)