A great public benefactor, he spent lavishly on public works and monuments in numerous sites, including Athens and his homeland, Marathon.
The Nymphaeon, also known as Herodes Atticus' Exedra, was built in 160 AD and contributed greatly to the function of the sanctuary as, until then, there was shortage of fresh drinking water especially during the Olympics, when the Altis teemed with visitors and water had to be drawn from numerous wells around the site.
The monumental reservoir gathered spring water, which was distributed through a dense network of pipes. What was even more stunning, however, was the opulence of the monument: the semi-circular structure was crowned by an apse, which housed numerous statues representing Zeus and members of the families of Herodes and the Roman Emperor Antoninus Pius, including the future emperor Marcus Aurelius, to whom Herodes had been a private tutor appointed by Antoninus himself. In the middle of the apse stood a marble bull, which visitors can still admire at the Archaeological Museum of Olympia. The reservoir proper, however, has been poorly preserved, also due to the fact that many architectural components were broken away and used in the construction of the nearby basilica in the 5th century AD. Modern pilgrims can only imagine the grandeur of the original monument with the aid of illustrations.