Ptolemy II Philadelphus, the Macedonian ruler of Egypt, renamed it Philadelphia. The city became part of the Nabataean kingdom until 106 CE when Philadelphia came under Roman control and joined the Decapolis. The ancient city consisted of the citadel, or acropolis, built in three terraces rising from west to east on a steep-sided, L-shaped hill, and the lower town in the valley of the Wadi ‛Amman to the south. Below the citadel, along the south bank of the wadi, were the forum, the odeium, the theatre and the nymphaeum, all built under the Roman Empire. The theatre (2nd century) is built into the hill; its auditorium has been restored, and part of the stage building, with Corinthian columns and curved exedra, remains in place. The city came under Byzantine rule before being conquered by the Muslims in 635 CE.