Pergamon was one of the most brilliant cultural centers of the Hellenistic era. It seems that the Temple of Trajan (98-117 AD) was erected by his successor Hadrian. In the temple were discovered two colossal marble statues of Trajan and Hadrian. There are other temples in the site, of Zeus, Dionysus, Serapis and Demeter. Also seen in the site are the city's walls, a theater, a water supply system, a gymnasium, a sacred way and a passageway.