Valley of Rephaim

The Valley of Rephaim (, "Emeq Rephaim") (; , R.V.) or Valley of the Rephaim, is a valley descending southwest from Jerusalem to Nahal Sorek below, it is an ancient route from the coastal plain to the Judean Hills, probably named after the legendary race of giants. Emek Refaim (), the German Colony in Jerusalem, takes its name from this valley.
Biblical story.
When David became king over all Israel, the Philistines, judging that he would now become their uncompromising enemy, made a sudden attack upon Hebron, compelling David to retire from it. He sought refuge in "the hold" at Adullam (), and the Philistines took up their position in (or raided) the valley of Rephaim, on the west and south-west of Jerusalem. Thus all communication between Bethlehem and Jerusalem was intercepted. While David and his army were encamped here, there occurred the battle narrated in and . Having obtained divine direction, David led his army against the Philistines, and gained a complete victory over them. The scene of this victory was afterwards called Baal-perazim.
A second time, however, the Philistines rallied their forces in this valley ( and ). Again, warned by a divine saying about hearing a marching sound in the tops of the baka trees (הבכאים, KJV "mulberry trees", most modern versions "balsam"), David led his army to Gibeon, and attacked the Philistines from the south, inflicting on them another severe defeat, and chasing them with great slaughter to Gezer. There David kept in check these enemies of Israel and in consequence his fame grew.
Railway.
The Tel Aviv – Jerusalem railway, originally known as the Jaffa–Jerusalem railway, uses the entire length of the Valley of the Rephaim from Jerusalem to its junction with Nahal Sorek.