The herm as a sculpture type made its appearance in Greece at the end of the 6th century B.C. Essentially a rectangular stele topped with the head of the god Hermes, usually with male genitalia in relief on the front of the shaft, herms were erected on streets and crossroads. The Athenian tyrant Hipparchos is known to have erected 150 herms throughout Attica. The form was adapted in the Hellenistic period when the head of the god was replaced by famous individuals, such as philosophers and statesmen. The type continued to be popular with the Romans. Draped herms, especially female, are comparatively rare. Four draped female herms, now in the Palazzo dei Conservatori, Rome, perhaps once served as caryatids (see p. 110, pl. 492-494 in Bieber, Ancient Copies, Contributions to the History of Greek and Roman Art).