Easton's Bible Dictionary
There were in Palestine (1) cities, (2) unwalled villages, and (3) villages with castles or towers (1 Chronicles 27:25). Cities, so called, had walls, and were thus fenced. The fortifications consisted of one or two walls, on which were towers or parapets at regular intervals (2 Chronicles 32:5; Jeremiah 31:38). Around ancient Jerusalem were three walls, on one of which were ninety towers, on the second fourteen, and on the third sixty. The tower of Hananeel, near the north-east corner of the city wall, is frequently referred to (Nehemiah 3:1; 12:39; Zechariah 14:10). The gateways of such cities were also fortified (Nehemiah 2:8; 3:3, 6; Judges 16:2, 3; 1 Samuel 23:7).
The Hebrews found many fenced cities when they entered the Promised Land (Numbers 13:28; 32:17, 34-42; Joshua 11:12, 13; Judges 1:27-33), and we may estimate the strength of some of these cities from the fact that they were long held in possession by the Canaanites. The Jebusites, e.g., were enabled to hold possession of Jerusalem till the time of David (2 Samuel 5:6, 7; 1 Chronicles 11:5).
Several of the kings of Israel and Judah distinguished themselves as fortifiers or "builders" of cities.