John Gill 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, he built cities in the mountains of Judah
In the mountainous part of it, the hill country of Judea, (Luke 1:65) ,

and in the forests he built castles and towers ;
for the safety of travellers, and of shepherds and their flocks, see (2 Chronicles 26:10) .