Gerasa (mod. Gerash or Jerash), a city of Palestine, and a member of the league known as the Decapolis (q.v.), situated amid the mountains of Gilead, about 1757 ft. above the sea, 20 m. from the Jordan and 21 m. N. of Philadelphia. Of its origin nothing is known; it has been suggested that it represents the biblical Ramoth Gilead. From Josephus we learn that it was captured by Alexander Jannaeus (c. 83 B.C.), rebuilt by the Romans (c. A.D. 65), burned by the Jews in revenge for the massacre at Caesarea, and again plundered and depopulated by Annius, the general of Vespasian; but, in spite of these disasters, it was still in the 2nd and 3rd centuries of the Christian era one of the wealthiest and most flourishing cities of Palestine. It was a centre of Greek civilization, devoted especially to the worship of Artemis, and producing famous teachers, of whom Stephen the Byzantine mentions Ariston, Kerykos and Plato. As late as 1121 the soldiers of Baldwin II. found it defended by a castle built by a king of Damascus; but at the beginning of the following century the Arabian geographer Yaqut speaks of it as deserted and overthrown. The ruins of Jerash, discovered about 1806, and since then frequently visited and described, still attest the splendour of the Roman city. They are distributed along both banks of the Kerwan, a brook which flows south through the Wadi-ed-Dēr to join the Zerka or Jabbok; but all the principal buildings are situated on the level ground to the right of the stream. The town walls, which can still be traced and indeed are partly standing, had a circuit of not more than 2 m., and the main street was less than half a mile in length; but remains of buildings on the road for fully a mile beyond the south gate, show that the town had outgrown the limit of its fortifications. The most striking feature of the ruins is the profusion of columns, no fewer than 230 being even now in position; the main street is a continuous colonnade, a large part of which is still entire, and it terminates to the south in a forum of similar formation. Among the public buildings still recognizable are a theatre capable of accommodating 6000 spectators, a naumachia (circus for naval combats) and several temples, of which the largest was probably the grandest structure in the city, possessing a portico of Corinthian pillars 38 ft. high. The desolation of the city is probably due to earthquake; and the absence of Moslem erections or restorations seems to show that the disaster took place before the Mahommedan period.
The town is now occupied by a colony of Circassians, whose houses have been built with materials from the earlier buildings, and there has been much destruction of the interesting ruins. “The country of the Gerasenes” (Matt. viii. 28 and parallels; other readings, Gadarenes, Gergesenes) must be looked for in another quarter—on the E. coast of the Sea of Galilee, probably in the neighbourhood of the modern Khersa (C.W. Wilson in Recovery of Jerusalem, p. 369).