Zech 2:1-5 Zechariah has a vision of a young man with a measuring line. He is surveying the old walls of Jerusalem "to see how wide and how long it is." (Zechariah 2:2)
An angel tells the young man that Jerusalem will become so wealthy and prosperous that it will be too big to fit within the old city walls:
"Jerusalem will become a city without walls, because there will be so many people and cattle in it." (Zechariah 2:4)
Jerusalem's city walls near the Tower of David (EdoM)
Instead of tall walls, the LORD will keep Jerusalem safe: "I will be a wall of fire around it... And I will be the glory within it." (Zechariah 2:5)
Zech 2:6-13 The LORD calls the exiles in Babylon to come back home to Jerusalem:
"Shout and be glad, Jerusalem. I am coming, and I will live among you," says the LORD. "At that time people from many nations will join with the LORD and will become my people. Then I will live among you." (Zechariah 2:10-11)