The site of the sanctuary was first systematically excavated by a French team in 1829[3] then the German expedition headed by Georg Treu from 1875–81, and the results published in a five volume report by Ernst Curtius and Friedrich Adler, Olympia: Die Ergebnisse der von dem deutschen Reich veranstalteten Ausgrabung, 1892-7.
Since the first reconstruction of the pediments by Treu in 1897 and the rejection of Pausanias's ascription to Paionios of Mende and Alkamenes on grounds of chronology[4] the temple decoration is now commonly attributed to the putative Olympia Master,[5] one amongst a studio of five sculptors.
The Olympia Master's work achieves a complexity of emotion that exceeds the conventions of the archaic; we find pathos, hubris, tension, exhaustion, disgust – markedly so in his characterization of Heracles, nuances lost to the idealised art of the later 5th century.
The metopes depict the twelve Labours of Hercules, a figure of singular importance to the temple, as it was he, a son of Zeus, who according to legend marked out the sanctuary and instituted the Olympic Games.
Several of the heads of the pediment figures have unworked bosses suggesting that a pointing process was used from clay or wood models, it is highly unusual to find traces of technique on work of the era.