The Temple of Olympian Zeus was built by the Hellenophile Emperor, Hadrian (117-132 AD). This, the most monumental temple of its time, was dedicated to Zeus, the father of gods. Initially there were 104 columns; of which only fifteen remain standing today, with a sixteenth lying on the ground.

There were originally three rows of eight columns each on the east and west sides, and two double rows along the two long sides. The temple was built on the site of other earlier temples, also dedicated to Olympian Zeus. The ancient Athenians considered the shrine to Olympian Zeus as one of the oldest in the city. North of the Olympieion, inside a small park, one can still see the remains of a propylaeum that was part of the Themistoclean wall, as well as a Roman bath.