Masonry structures that serve as barriers, mark boundaries, or form enclosures. As long as man has been constructing houses and cities, he has been building walls out of many materials, in a variety of designs, to serve a number of purposes. The size and strength of structures largely depend on the construction of the walls and the materials used in making them.

The walls of David’s palace were of cut stone. (2Sa 5:11) Similarly, the outside walls of Solomon’s temple, it appears, were of quarried stone, with some of their interior surfaces covered over with cedar boards. (1Ki 6:2, 7, 15) These interior wooden panels, in turn, were elaborately decorated with carvings and overlays of gold. (1Ki 6:29; 1Ch 29:4; 2Ch 3:4, 7) The interior wall surfaces of Belshazzar’s palace were plastered. (Da 5:5) The walls of the homes of the people in general were usually of simple construction​—sun-dried bricks, uncut stones, or plastered material over a wooden framework. Sometimes the surface was whitewashed.​—Ac 23:3.

City Walls. In ancient times fear caused people to erect protective walls around large cities to prevent enemy invasion. (1Ki 4:13; Isa 25:12) The inhabitants of the small “dependent towns” round about (Nu 21:25) likewise took refuge within the walled city if attacked. The Mosaic Law made a legal distinction between walled and unwalled towns, as to the rights of house owners. (Le 25:29-31) The walls not only provided a physical barrier between city residences and an enemy but also afforded an elevated position atop which the defenders could protect the walls from being undermined, tunneled through, or breached by battering rams. (2Sa 11:20-24; 20:15; Ps 55:10; Ca 5:7; Isa 62:6; Eze 4:1, 2; 26:9) As a countermeasure, attacking forces sometimes threw up siege walls as shields behind which to assault the city walls.​—2Ki 25:1; Jer 52:4; Eze 4:2, 3; 21:22; see FORTIFICATIONS.

Other Walls. Stone walls were often built to hedge in vineyards or fields, and to form corrals or sheep pens. (Nu 22:23-25; Pr 24:30, 31; Isa 5:5; Mic 2:12; Hab 3:17) And there were also walls that served for embankment purposes along terraced hillsides. (Job 24:11) These walls were of a fairly permanent nature, built of undressed fieldstones and sometimes set in clay or mortar.

Symbolic Walls. In the Scriptures, walls are sometimes mentioned in a figurative way as pictorial of protection and safety (1Sa 25:16; Pr 18:11; 25:28) or as a symbol of separation. (Ge 49:22; Eze 13:10) In this latter sense Paul wrote the Ephesians: “For he [Christ] is our peace, he who made the two parties one and destroyed the wall in between that fenced them off.” (Eph 2:14) Paul was well acquainted with the middle wall in Jerusalem’s temple courtyard, which carried a warning sign to the effect that no non-Jew was to go beyond that wall under penalty of death. However, when Paul wrote to the Ephesians in 60 or 61 C.E., though he may have alluded to it in an illustrative way, he actually did not mean that the literal wall had been abolished, for it was still standing. Rather, the apostle had in mind the Law covenant, which had acted as a dividing wall between Jews and Gentiles for centuries. On the basis of Christ’s death nearly 30 years previously, that symbolic “wall” had been abolished.

Jeremiah was told he would be like fortified walls of copper against those that opposed him.  (Jer 1:18, 19; 15:20) In another illustration, God’s people, though dwelling as in a city without literal walls, therefore seemingly defenseless, enjoy peace and security because of God’s invisible help. (Eze 38:11) Or from another point of view, a strong city would be one having Jehovah as “a wall of fire” (Zec 2:4, 5), or having walls of salvation set up by Jehovah, rather than ones of mere stone and brick. (Isa 26:1) “The holy city, New Jerusalem,” which comes down out of heaven, is said to have “a great and lofty wall” of jasper, the height of which is 144 cubits (64 m; 210 ft), and it is said to have 12 foundation stones consisting of precious jewels engraved with the names of the 12 apostles.​—Re 21:2, 12, 14, 17-19.