Concise Bible Dictionary:
A valley on the south of Jerusalem, in which the Philistines gathered themselves against Israel, and where David twice signally defeated them (2 Sam. 5:18, 22; 2 Sam. 23:13; 1 Chron. 11:15; 1 Chron. 14:9-17; Isa. 17:5). In the AV it is twice called the “VALLEY OF THE GIANTS” (Josh. 15:8; Josh. 18:16). Identified with el Bukeia, 31° 45' N, 35° 13' E.
Plain of Rephaim from Jaffa Gate.