Revelation 21:13-16

There were three gates on the east and three gates on the north and three gates on the south and three gates on the west. And the wall of the city had twelve foundation stones, and on them were the twelve names of the twelve apostles of the Lamb. The one who spoke with me had a gold measuring rod to measure the city, and its gates and its wall. The city is laid out as a square, and its length is as great as the width; and he measured the city with the rod, fifteen hundred miles; its length and width and height are equal.