The term poikilos is quasi-generic and reflects the fact that the interior of both stoas was lined with paintings by the most famous artists of the time. Built quite late, around 350 BC, it was meant to become the east boundary of the Altis and a screen between the Stadium and the rest of the sanctuary; previously, the Temple of Zeus had been perfectly visible from the finishing line, and this may have been an issue in terms of religious correctness and the definition of separate rituals within the Games. By the 4th century BC, the once religious Games must have given way to an athletic event attended by thousands of people, whose profanity could taint the sacred enclosure. The quite impressive structure was almost 100 metres long; it consisted of an interior colonnade of unknown style and an exterior one comprising 44 Doric columns. It was named after its unique echo effect, with any sound produced within the building being repeated seven times, hence another popular name for the monument: Eptaechos (=of seven sounds).
Another monument confirming the grand status of the sanctuary long after the Classical Era, as well as the prominence of the Echo Stoa, is the one erected in front of the stoa by Ptolemy II and his sister and wife Arsinoe II in the mid-3rd century BC. The two ends of the large stone platform, measuring 20 metres in length and 4 metres in width, were decorated with two Ionic columns, on which stood two gilded statues representing the king and queen. Today, visitors can still see parts of the Stoa, as well as the stone platform and parts of the Ionic columns of Ptolemy’s monument.