A large rectangular building to the west of the Temple of Zeus, identified as the workshop where Pheidias and his assistants created the great chryselephantine statue of Zeus around 435 BC. The building has the same dimensions and orientation as the Parthenon in Athens — deliberately, since the statue's proportions were designed to fit it. In the Byzantine period the workshop was converted into a church, which is partly why its walls survived to a useful height.
Archaeological excavation in the mid-20th century confirmed the identification through the discovery of sculptor's tools, clay moulds used for casting the gold drapery panels, and a mug with Pheidias' name scratched into it. The site gives you a rare sense of the industrial process behind ancient sculpture — not heroic genius in a pure white space but craftsmen working in a large, dusty shed.