Boyd’s Bible Dictionary:
Altars, temples, and dedicated places originally on high ground
(Gen. 12:88And he removed from thence unto a mountain on the east of Beth-el, and pitched his tent, having Beth-el on the west, and Hai on the east: and there he builded an altar unto the Lord, and called upon the name of the Lord. (Genesis 12:8); Judg. 6:2525And it came to pass the same night, that the Lord said unto him, Take thy father's young bullock, even the second bullock of seven years old, and throw down the altar of Baal that thy father hath, and cut down the grove that is by it: (Judges 6:25); Isa. 65:77Your iniquities, and the iniquities of your fathers together, saith the Lord, which have burned incense upon the mountains, and blasphemed me upon the hills: therefore will I measure their former work into their bosom. (Isaiah 65:7); Jer. 3:66The Lord said also unto me in the days of Josiah the king, Hast thou seen that which backsliding Israel hath done? she is gone up upon every high mountain and under every green tree, and there hath played the harlot. (Jeremiah 3:6)). When the groves and mounts of idolatry overshadowed true worship, “high places” became a reproach.
Concise Bible Dictionary:
The word commonly used for the high place is bamah, signifying what is high or elevated (compare Ezek. 20:2929Then I said unto them, What is the high place whereunto ye go? And the name thereof is called Bamah unto this day. (Ezekiel 20:29)), and then the hills on which altars were erected. There were such places in Canaan before the Israelites entered it, which they were told to destroy (Num. 33:5252Then ye shall drive out all the inhabitants of the land from before you, and destroy all their pictures, and destroy all their molten images, and quite pluck down all their high places: (Numbers 33:52)). If the Israelites had such, God would destroy them and cut down their images (Lev. 26:3030And I will destroy your high places, and cut down your images, and cast your carcases upon the carcases of your idols, and my soul shall abhor you. (Leviticus 26:30)).
In the above passages the high places are connected with idolatry; but it would appear that before the temple was built, altars for the worship of God had been erected elsewhere than at the tabernacle. With Samuel at Zuph, there was “a sacrifice of the people” in the “high place” (God having forsaken the tabernacle at Shiloh, this disorder resulted). It was evidently on elevated ground, for they went up to it and came down (1 Sam. 9:12-2512And they answered them, and said, He is; behold, he is before you: make haste now, for he came to day to the city; for there is a sacrifice of the people to day in the high place: 13As soon as ye be come into the city, ye shall straightway find him, before he go up to the high place to eat: for the people will not eat until he come, because he doth bless the sacrifice; and afterwards they eat that be bidden. Now therefore get you up; for about this time ye shall find him. 14And they went up into the city: and when they were come into the city, behold, Samuel came out against them, for to go up to the high place. 15Now the Lord had told Samuel in his ear a day before Saul came, saying, 16To morrow about this time I will send thee a man out of the land of Benjamin, and thou shalt anoint him to be captain over my people Israel, that he may save my people out of the hand of the Philistines: for I have looked upon my people, because their cry is come unto me. 17And when Samuel saw Saul, the Lord said unto him, Behold the man whom I spake to thee of! this same shall reign over my people. 18Then Saul drew near to Samuel in the gate, and said, Tell me, I pray thee, where the seer's house is. 19And Samuel answered Saul, and said, I am the seer: go up before me unto the high place; for ye shall eat with me to day, and to morrow I will let thee go, and will tell thee all that is in thine heart. 20And as for thine asses that were lost three days ago, set not thy mind on them; for they are found. And on whom is all the desire of Israel? Is it not on thee, and on all thy father's house? 21And Saul answered and said, Am not I a Benjamite, of the smallest of the tribes of Israel? and my family the least of all the families of the tribe of Benjamin? wherefore then speakest thou so to me? 22And Samuel took Saul and his servant, and brought them into the parlor, and made them sit in the chiefest place among them that were bidden, which were about thirty persons. 23And Samuel said unto the cook, Bring the portion which I gave thee, of which I said unto thee, Set it by thee. 24And the cook took up the shoulder, and that which was upon it, and set it before Saul. And Samuel said, Behold that which is left! set it before thee, and eat: for unto this time hath it been kept for thee since I said, I have invited the people. So Saul did eat with Samuel that day. 25And when they were come down from the high place into the city, Samuel communed with Saul upon the top of the house. (1 Samuel 9:12‑25)). At the beginning of the reign of Solomon the people sacrificed in high places because the temple was not yet built. This was failure, for we read that “Solomon loved the Lord, walking in the statutes of David his father: only he sacrificed and burnt incense in high places” (1 Kings 3:2-42Only the people sacrificed in high places, because there was no house built unto the name of the Lord, until those days. 3And Solomon loved the Lord, walking in the statutes of David his father: only he sacrificed and burnt incense in high places. 4And the king went to Gibeon to sacrifice there; for that was the great high place: a thousand burnt offerings did Solomon offer upon that altar. (1 Kings 3:2‑4)). The tabernacle was there at Gibeon (1 Chron. 16:3939And Zadok the priest, and his brethren the priests, before the tabernacle of the Lord in the high place that was at Gibeon, (1 Chronicles 16:39); 2 Chron. 1:33So Solomon, and all the congregation with him, went to the high place that was at Gibeon; for there was the tabernacle of the congregation of God, which Moses the servant of the Lord had made in the wilderness. (2 Chronicles 1:3)), so that it appeared to be the right place to go to, and it was where God appeared to Solomon in the night; yet it was “the great high place.” The reason of this implied disapproval is doubtless because the ark was not there, the symbol of God’s presence, which was the true place of worship. At the close of Solomon’s life he sinned greatly in building a high place for the gods of all his strange wives (1 Kings 11:7-87Then did Solomon build an high place for Chemosh, the abomination of Moab, in the hill that is before Jerusalem, and for Molech, the abomination of the children of Ammon. 8And likewise did he for all his strange wives, which burnt incense and sacrificed unto their gods. (1 Kings 11:7‑8)). On the division of the kingdom, Jeroboam set up his idols and “ordained him priests for the high places, and for the devils, and for the calves which he had made” (2 Chron. 11:1515And he ordained him priests for the high places, and for the devils, and for the calves which he had made. (2 Chronicles 11:15)). With these two examples it is not surprising that in the whole land there were many high places. Hezekiah and Josiah zealously destroyed the high places, which included the buildings thereon and the idols connected therewith. The word bamah is used apparently for any idolatrous erection, for we once read of high places in a valley (Jer. 7:3131And they have built the high places of Tophet, which is in the valley of the son of Hinnom, to burn their sons and their daughters in the fire; which I commanded them not, neither came it into my heart. (Jeremiah 7:31)).
The term “high places” has another application under the Hebrew word ramah, which also signifies “exalted”; for Israel is charged with making a high place in every street, and at every head of the way, which doubtless refers to some shrine or symbol of idolatry connected with abominable practices (Ezek. 16:24-25,31,3924That thou hast also built unto thee an eminent place, and hast made thee an high place in every street. 25Thou hast built thy high place at every head of the way, and hast made thy beauty to be abhorred, and hast opened thy feet to every one that passed by, and multiplied thy whoredoms. (Ezekiel 16:24‑25)
31In that thou buildest thine eminent place in the head of every way, and makest thine high place in every street; and hast not been as an harlot, in that thou scornest hire; (Ezekiel 16:31)
39And I will also give thee into their hand, and they shall throw down thine eminent place, and shall break down thy high places: they shall strip thee also of thy clothes, and shall take thy fair jewels, and leave thee naked and bare. (Ezekiel 16:39)). They courted the favor of the heathen by adopting their idolatrous worship and customs.