A spectacular semicircular fountain house built around AD 160 by the Athenian magnate Herodes Atticus and his wife Regilla, who was a priestess of Demeter at Olympia. The structure brought fresh water to the sanctuary from a source to the east and distributed it through a basin running along the face of the building, fed by an upper and lower semi-circular pool flanked by niches for statues.
At its peak the Nymphaeum was one of the most elaborate structures on the site, covered in marble and decorated with dynastic sculpture. Today the curved foundations and the base of the upper basin survive, enough to suggest the building's theatre. It marked a high point of Roman patronage at Olympia and also the beginning of the sanctuary's gradual transformation from Greek religious site to Roman showpiece.