After the conquest of Athens by Sylla, the Romans gave Athens a special status of autonomy by strong intellectual movement that was in it. Athens continued to gather important literary figures of the era while many Roman Emperors acquired homes in the city. The major works of the Roman period held in Athens by the Emperor Hadrian in the period between 117 and 138 AD. Hadrian completed the Temple of Olympian Zeus, and proceeded to the construction of many important public buildings like the library, gymnasium, etc. aqueduct. In his honor, the Athenians built the arch was known as Hadrian's Gate.
(from Wikipedia with add-ons from C. Theodorou)