My dear friends in Christ, “WALLED IN City” is precisely the analogy that Christ had in mind in appointing Peter to Head and Govern His New Church, and to whom He entrust all of the Key’s to heavens access.
Jerusalem was such a city at the time of Peters appointment as Christ “VISAR” and was given unlimited powers of Governance, answerable only to and DIRECTLY to Christ Himself.
Matthew 16:15-19  Simon Peter answered and said: Thou art Christ, the Son of the living God.  And Jesus answering, said to him: Blessed art thou, Simon Bar-Jona: because flesh and blood hath not revealed it to thee, but my Father who is in heaven.  And I say to thee: That thou art Peter; and upon this rock I will build my church, and the gates of hell shall not prevail against it. And I will give to thee the keys of the kingdom of heaven. And whatsoever thou shalt bind upon earth, it shall be bound also in heaven: and whatsoever thou shalt loose upon earth, it shall be loosed also in heaven.
Manners & Customs: City Walls
City Walls in the Ancient World
Ancient Walls The Oriental Town or City WALLS DIFFERENCE BETWEEN CITY AND VILLAGE, AS TO WALLS. In early Old Testament times the villages were smaller places of abode without walls around them, whereas the cities or towns were larger places that had walls around them. The Mosaic Law made such a distinction: “If a man sell a dwelling house in a walled city” (Leviticus 25:29). “But the houses of the villages which have no wall round about them” (Leviticus 25:31). The villages were often located near a fortified city upon which they were more or less dependent. Thus the city was the metropolis of the villages. We often read in the Bible of “cities and their villages,” Some speak of the expression: “cities and their daughters,” indicating a mother-city, and her dependent villages surrounding her (cf. Joshua 15:45 and 17:11).1 Walls a part of city fortifications. In Bible times most cities were walled and fortified for protection against an enemy. Those living in a city without walls would be interested in having walls built for them. Often when the Bible says that a certain character built a city, what is meant is not that a new site was located and a new city was built, but rather that a city already inhabited was supplied with walls entirely around its confines.2 It was thus that Solomon built “Bethhoron the upper, and Beth-horon the nether, fenced cities, with walls, gates, and bars” (II Chronicles 8:5). [Manners And Customs of Bible Lands]
City Walls in Naves Topical Bible Of Bashan, destroyed by the Israelites De 3:5,6 -Of Jericho Jos 2:15; 6 -Of Jerusalem See JERUSALEM -Of Babylon Jer 51:44 -Broad Jer 51:58 -Of Beth-shan 1Sa 31:10 -Of Rabbah 2Sa 11:20 -Of Abel 2Sa 20:15,21 -Houses built upon Jos 2:15 -Double 2Ki 25:4; Isa 22:11 -Sentinels on See WATCHMAN -FIGURATIVE Of the new Jerusalem Re 21:12,14,17-21
Walls in Easton’s Bible Dictionary Cities were surrounded by walls, as distinguished from “unwalled villages” (Ezek. 38:11; Lev. 25:29-34). They were made thick and strong (Num. 13:28; Deut. 3:5). Among the Jews walls were built of stone, some of those in the temple being of great size (1 Kings 6:7; 7:9-12; 20:30; Mark 13:1, 2). The term is used metaphorically of security and safety (Isa. 26:1; 60:18; Rev. 21:12-20). (See FENCE ¯T0001321.)
Manners & Customs: City Gates
City Gates in the Ancient World
Ancient Gates Character of gates. The gates of an Oriental city were of course connected with the walls; nevertheless, they were in a sense a structure by themselves. They were usually made of wood or stone, or wood that had been armored with metal. The Psalmist speaks of gates of brass (copper), and gates of iron (Psalm 107:16). Often they were two-leaved (Isaiah 45:1), and were provided with heavy locks and bars (I Samuel 23:7). Sometimes a city or town had two walls and therefore two gates with a space between them. A sentinel was stationed in the tower of the first gate. When David was at Mahanaim awaiting the result of the battle with Absalom, Scripture says: “And David sat between the two gates: and the watchman went up to the roof over the gate unto the wall, and lifted up his eyes, and looked, and behold a man running alone” (II Samuel 18:24). This space between the gates was used for many purposes. [Manners And Customs of Bible Lands]
Gate in Easton’s Bible Dictionary (1.) Of cities, as of Jerusalem (Jer. 37:13; Neh. 1:3; 2:3; 3:3), of Sodom (Gen. 19:1), of Gaza (Judg. 16:3). (2.) Of royal palaces (Neh. 2:8). (3.) Of the temple of Solomon (1 Kings 6:34, 35; 2 Kings 18:16); of the holy place (1 Kings 6:31, 32; Ezek. 41:23, 24); of the outer courts of the temple, the beautiful gate (Acts 3:2). (4.) Tombs (Matt. 27:60). (5.) Prisons (Acts 12:10; 16:27). (6.) Caverns (1 Kings 19:13). (7.) Camps (Ex. 32:26, 27; Heb. 13:12). The materials of which gates were made were, (1.) Iron and brass (Ps. 107:16; Isa. 45:2; Acts 12:10). (2.) Stones and pearls (Isa. 54:12; Rev. 21:21). (3.) Wood (Judg. 16:3) probably. At the gates of cities courts of justice were frequently held, and hence “judges of the gate” are spoken of (Deut. 16:18; 17:8; 21:19; 25:6, 7, etc.). At the gates prophets also frequently delivered their messages (Prov. 1:21; 8:3; Isa. 29:21; Jer. 17:19, 20; 26:10). Criminals were punished without the gates (1 Kings 21:13; Acts 7:59). By the “gates of righteousness” we are probably to understand those of the temple (Ps. 118:19). “The gates of hell” (R.V., “gates of Hades”) Matt. 16:18, are generally interpreted as meaning the power of Satan, but probably they may mean the power of death, denoting that the Church of Christ shall never die.