What archaeological evidence identified Phidias's workshop at Olympia?

Archaeological excavations conducted between 1954 and 1958 at Olympia provided definitive evidence to identify the workshop of the sculptor Phidias, located just outside the Altis to the west of the Temple of Zeus.1

The identification was confirmed by the discovery of a significant mass of waste material from the artist's atelier in the deep layers of the building. This evidence included:1

• Tools and Materials: Researchers found various tools, as well as slivers and worked fragments of ivory and bone.1
• Molds: A large number of terra-cotta molds were recovered. These molds, which were of a heavy fabric similar to roof tiles and sometimes reinforced with iron rods, were used to hammer thin sheets of gold into the drapery for the Statue of Zeus.1
• Personal Artifact: A piece of pottery—specifically a ribbed mug—was found with an inscription on the bottom that clearly reads, "I am [the property] of Phidias".1

Pottery found alongside this debris indicates the workshop was active around 430 BCE, the period during which Phidias was creating his masterpiece.1