Arch of Hadrian

But they also frame three rectangular openings, and the middle opening itself was, in antiquity, closed by a thin marble sheet that probably had a painting of the Athenian hero Theseus on the side looking toward the Acropolis, and a painting of Hadrian on the side looking toward the Temple of Olympian Zeus.

This structure is called, appropriately enough, the Arch of Hadrian, and it was commissioned and set up by the Athenians in honor of the emperor.

Now importantly, at the top of the first story, the arch had an inscription on both of its sides.

On the side facing the Acropolis, the inscription reads, "This is Athens, the ancient city of Theseus."