Charles Ellicott Commentary 2 Chronicles 27:4

"Moreover he built cities in the hill-country of Judah, and in the forests he built castles and towers." — 2 Chronicles 27:4 (ASV)

Moreover. — Literally, and he built cities in the hill region of Judah. (Compare to 2 Chronicles 26:10.)

Castles. — Bîrânîyôth; a term explained at 2 Chronicles 17:12. The contemporary prophets denounced the popular confidence in “fenced cities” as a kind of treason against Jehovah, who was Himself the shield and fortress of His people (Psalms 18:1; Isaiah 12:2). Israel hath forgotten his Maker, and buildeth palaces; and Judah hath multiplied fenced cities: but I will send a fire upon his cities, and it shall devour the palaces thereof (Hosea 8:14. Compare to Isaiah 2:15; Isaiah 17:3–4).