Mamre in the Old Testament
Genesis 13:18 refers to "the plain (rather the oaks or terebinths) of Mamre"; Gen. 14:13,24, brother of Eshcol, friend and ally of Abraham.
The chieftain had planted the terebinths, or was associated with them as his tenting place; so "the oak of Deborah" (Judg. 4:5).
Mamre was less than a mile from Hebron (Josephus, B. J. 4:9, section 7); but Robinson makes it two Roman miles off, now the hill er Rameh. Constantine, to suppress the superstitions veneration to the terebinths, erected a basilica or church on the spot.
That it was on an elevation appears from the record that Machpelah faces it (Gen. 23:17-19; 25:9). Abram resided under the oak grove shade in the interval between his stay at Bethel and at Beersheba (Gen. 13:18; 18:1; 20:1; 21:31).
If Machpelah be on the N.E. side of the Hebron valley, then Mamre as "facing it" must have been on the opposite slope, where the governor's house now is.
International Standard Bible Encyclopedia, which is in the public domain (with minor edits).