The Gate of Hadrian (also called Arch of Hadrian) in Athens is a monumental gate of pentelic marble that was erected ca. 132. It formed the passage from old Athens to the new Athens that the Roman emperor Hadrian had built. The gate has two identical facades, but different inscriptions in Greek letters. On the northwest side, towards the Acropolis, it says: 'This is Athens, the ancient city of Theseus'. On the southeast side, towards the Temple of Olympian Zeus, it reads: 'This is the city of Hadrian and not of Theseus'.
The gate spanned a pre-existing road that ran from the old city to the southwestern part of the city. It was not part of a city wall. It is usually assumed that its function was to mark the separation between the old city and the new part of the city that Hadrian had built, but it is also thought that the residents of Athens wanted to honor Hadrian for his building activities with the arch as the new founder of their city.
The arch is 18 m high, 12.5 m wide and 2.30 m thick. On either side of the passage, the arch was decorated with Corinthian columns, of which only the bases and upper parts can now be seen. On top of the arch is a colonnade of four columns, crowned by a pediment between the two middle columns.