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]