High places means in the bible: It was a custom among early nations to build altars on hillstops. Gen. 12-8; 22:2-4 and 31:54. The settlement of Canaan saw the establishment of heathen altars on several hills. They were destroyed by Num. 33:52; Deut. 12:2-3. Several high locations Judg. were home to Altars of Jehovah. 6:25-26; 1 Sam. 9:12-25; 10:5, 13; 1 Kgs. 3:2-4; 18:30; 1 Chr. 21:26. These altars were used as local centres for the worship of Jehovah. Many of these altars became the focal point for idolatry and were used to worship heathens. Josiah and Hezekiah, religious reformers, tried to consolidate worship in Jerusalem. It was easier to control and keep under control. The high places were also ordered removed. No sacrifices could be made anywhere else than Jerusalem 2 Kgs. 18:4, 22; 23; 2 Chr. 31:1;34:3; Deut. 12:11-14.
(in Bible Dictionary)