2 Kings 17:9

Did secretly. The Israelites were perfidious and deceitful in carrying on their iniquities. Often there was an outward show of religion and respectability, covering their base and immoral practices with a cloak of dissimulation. Pretending to serve Jehovah, they were actually engaging in practices that were directly contrary to the principles of His kingdom.

High places. At these centers gross forms of immorality often accompanied idolatrous worship (see Deut. 12:2, 3; Isa. 57:5-7; Jer. 2:20; 3:2). The native fertility cults of the land involved the worshipers in most shameful practices.

From the tower. The expression thus introduced signifies extent from one end of the country to the other (see ch. 18:8). There were towers for watchmen in the most remote sections, out in the fields, for purposes of protection; and there were large walled cities. The meaning is that the high places were established everywhere, in remote rural areas as well as in the great centers of population.