Jarash—ancient Gerasa— is located 23 mi. [37 km.] north of Amman (ancient Philadelphia). The large, 210 acres [85 ha.], Greco–Roman city was surrounded by a 1.5 mi. [2.5 km.] long wall. It was founded in the third century B.C. after the conquest of Alexander the Great in the area. It was situated on both sides of the Chrysorhas River (Wadi Jarash) that flows from north to south in this area.
In general, the residential areas of Gerasa were located on the eastern banks of the Chrysorhas, while the commercial, religious, administrative, and public structures were on the west side. Gerasa was one of the major cities of the “Decapolis.” Its “golden age” was from the late first to the early third centuries A.D. when many streets, temples, theaters, etc. were constructed—often on older remains. During the Byzantine (Christian) era the city had no less than six churches!
The city was weakened by a series of earthquakes in the eighth century, being devastated by the great quake of A.D. 749.