Philippeion, Sanctuary of Zeus (The Altis), Olympia, Greece
The Altis: began 10th century BCE; Philippeion: ca. 338 BCE
Although it is secluded near the west coast of the Peloponnese, Olympia became an important religious and athletic center in Greece. Its fame rests upon the Olympic Games, a highly-prestigious national festival held every four years to honor Zeus. The Altis, the sacred enclosure with its oaks, planes, pines, poplars and olive-trees, was first formed during the 10th and 9th centuries BCE, when the cult of Zeus was probably established.
The Philippeion in The Altis, was erected by Philip II, king of Macedonia, after his victory at the battle of Chaeroneia in 338 BCE. This tholos exemplifies the beginnings of Hellenistic architecture, especially in Macedonia. It is a circular structure with a colonnade of 18 Ionic columns on the outside, and a circular cella inside, with eight Corinthian columns around the wall.