The most eye-catching feature at the Temple of Athena Pronaia are these three fluted columns. They were part of 20 Doric columns once supporting Tholos. The circular marble structure was designed by Theodorus of Phocaea and built between 380 to 360 BC. The function of the classical building is unknown. Look closely at the remnants of a bas-relief inside of a metope (panel) on the horizontal entablature above the columns. This was part of a large frieze depicting mythological battles between Amazons (all female warriors) and centaurs (half-man, half-horse savages). Now notice the ruins on the upper terrace less than a half mile away. That is the main site of ancient Delphi. Along the way, you will encounter a ravine called Castalian Spring. This is where pilgrims and priests purified themselves with water. The first fountain on the route dates from 600 BC. You will also pass by the ruins of the Gymnasium.