Revelation 21:13-16

On the east side [there were] three gates, on the north three gates, on the south three gates, and on the west three gates. And the wall of the city had twelve foundation stones, and on them the twelve names of the twelve apostles of the Lamb (Christ). The one who was speaking 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, its length being the same as its width; and he measured the city with his rod—twelve thousand stadia (about 1,400 miles); its length and width and height are equal.