The temple of Zeus Olympios was built by the Philhellene 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 today only Fifteen remain standing, with a sixteenth lying on the ground. There used to be three rows of eight columns each on the east and west sides, and two double rows on the two long sides. The temple was built on the site of other earlier temples, also dedicated to Zeus Olympios. The ancient Athenians considered the shrine to Olympian Zeus as one of the oldest in the city.
North of the Olympieion, and inside a small park , one can still see the remains of a propylon, which was part of the Themistocleian wall, and a Roman bath. (1)
Built by the Athenians in honor of emperor Hadrian, a friend of the city of Athens. Hadrian himself passed under this glorious gate to attend the inauguration of the Temple of Olympian Zeus. The Corinthian style gate marked the border of the old city of Athens in relation of the new district that Hadrian built. On the east frieze, and under the arch, one can still see today the inscription <on this side it is Hadrian's city, not Theseus s >.On the west side of the gate, the inscription says < on this side is Athens, the former city of Theseus (1)
(1) Heritage Walks in Athens by Artemis Skoumbourdi, Elliniki Etaireia, p 76