'Stronghold' in the Bible

For we overthrow arrogant 'reckonings,' and every stronghold that towers high in defiance of the knowledge of God, and we carry off every thought as if into slavery--into subjection to Christ;

and with a mighty voice he cried out, saying, "Great Babylon has fallen, has fallen, and has become a home for demons and a stronghold for every kind of foul spirit and for every kind of foul and hateful bird.