The Arch of Hadrian, most commonly known in Greek as Hadrian’s Gate, is a monumental gateway resembling – in some respects – a Roman triumphal arch. It spanned an ancient road from the center of Athens, Greece, to the complex of structures on the eastern side of the city that included the Temple of Olympian Zeus. It has been proposed that the arch was built to celebrate the adventus of the Roman Emperor Hadrian and to honor him for his many benefactions to the city, on the occasion of the dedication of the nearby temple complex in 131 or 132 AD. It is not certain who commissioned the arch, although it is probable that the citizens of Athens or another Greek group were responsible for its construction and design. There were two inscriptions on the arch, facing in opposite directions, naming both Theseus and Hadrian as founders of Athens. While it is clear that the inscriptions honor Hadrian, it is uncertain whether they refer to the city as a whole or to the city in two parts: one old and one new. The early idea, however, that the arch marked the line of the ancient city wall, and thus the division between the old and the new regions of the city, has been shown to be false by further excavation. The arch is located 325m southeast of the Acropolis.Construction and designMaterial and designThe entire monument is made of Pentelic marble, from Mt. Pentelikon, 18.2 km northeast of the arch. Pentelic marble was used for the Parthenon and many other notable structures in Athens, although its quality can vary significantly. The marble used for the arch is of a lower grade that had more inclusions than that used in the best Athenian buildings. The arch was constructed without cement or mortar from solid marble, using clamps to connect the cut stones. It is 18m high, 13.5m wide, and 2.3m in depth. Its design is fully symmetrical from front to back and side to side.