In 338 BC, Philip II of the Kingdom of Macedon managed to defeat the traditional allied forces of Classical Greece (including the likes of Athens, Corinth, and Thebes) at Chaeronea, achieving a shift of power which would result in Alexander's campaign and the advent of the Hellenistic Era. There was no better method to advertise such a victory than to erect a splendid monument at a site of Panhellenic significance, and Philip's decision to choose Olympia confirms the unparalleled status of the site.
The Philippeion is the only circular structure in the Altis, as well as one of the finest examples of monumental architecture in Ancient Greece. Built at a premium location within the sacred enclosure, it was aptly dedicated by Philip to Zeus, and completed after his death (336 BC) by his son Alexander (later known as Alexander the Great). The latter, in his effort to establish a cult of the deified royal family of Macedon, commissioned the famous sculptor Leochares to create five chryselephantine statues (i.e., made of gold and ivory) to be placed inside the monument.
The main frame of this particularly elegant building was defined by eighteen Ionic columns on a circular marble base, while the roof was laid with marble tiles and crowned with a bronze poppy. The Greek travel writer Pausanias, who saw the building in the 2nd century AD, records that the interior was covered with limestone slabs, painted in red stucco with white joints, in imitation of a baked brick surface. The five statues of the royal family (representing Alexander, his parents Philip and Olympiad, as well as Philip's parents Amyntas and Euridice) were placed just opposite the entrance, on a semi-circular podium. Today, visitors may not be able to admire the long lost statues, though they have access to a semi-restored version of the monument. In 2004, on the occasion of the Athens Olympics, the Berlin Archaeological Museum returned ten architectural components to the site, thus opening the way to the partial restoration completed in 2005.