South of the Heraion was the Pelopion, a funerary monument (cenotaph) dedicated to Pelops, a much venerated Elean hero. According to Pausanias (V, 13, 1) this monument was dedicated by Hercules, a descendant of Pelops. Beneath the Pelopion lies a prehistoric tumulus (Early Helladic, approximately 2500 BC) and its enclosure. The earliest structure inside the Altis, its top was still visible in the Classical period.

In the sixth century BC the Pelopion consisted of a small eminence, two metres high. In the fifth century BC this was surrounded by an irregular five-sided enclosure with a simple entrance in the south-west corner. In the late fifth century BC, the entrance was embellished by a stone Doric portico. Inside the enclosure were trees, mostly poplars, and statues. According to Pausanias (V, 13, 2), once a year the magistrates sacrificed a black ram to honor Pelops and whoever ate from the sacrificed animal was not allowed to enter the temple of Zeus.

A wealth of archaeological finds - mostly pottery and terracotta and bronze animal and human figurines, many of them displayed in the Olympia Archaeological Museum - were uncovered during the early and recent German excavations.