“Him that overcometh will I make a pillar in the temple of my God, and he shall go no more out; and I will write upon him the name of my God, and the name of the city of my God, which is new Jerusalem, which cometh down out of heaven from my God: and I will write upon him my new name.” (Revelation 3 v 12)
After John witnesses the new heaven and a new earth ‘that no longer has any sea’, an angel takes him ‘in the Spirit’ to a vantage point on ‘a great and high mountain’ to see the New Jerusalem's descent. The enormous city comes out of heaven down to the new earth. John's elaborate description of the New Jerusalem retains many features of the Garden of Eden and the paradise garden, such as rivers, a square shape, a wall, and the Tree of Life.
According to John, the New Jerusalem is ‘pure gold, like clear glass’ and its ‘brilliance like a very costly stone, as a stone of crystal-clear jasper.’ The street of the city is also made of ‘pure gold, like transparent glass.’ The base of the city is laid out in a square and surrounded by a wall made of jasper. It says in Revelation 21:16 that the height, length, and width are equal and they measure 12,000 stadia (2200 km).
John writes that the wall is 144 cubits, which is assumed to be the width since the length is mentioned previously. 144 cubits are about equal to 65 metres, or 72 yards. It is important to note that 12 is the square root of 144. The number 12 is very important to God, and the divine order which it represents. The four sides of the city represented the four cardinal directions (North, South, East, and West.) In this way, New Jerusalem was thought of as an inclusive place, with gates accepting all of the 12 tribes of Israel from all corners of the earth.
The angel measures the city with a golden rod or reed, and records it as 12,000 stadia by 12,000 stadia at the base, and 12,000 stadia high. A stadion is usually stated as 185.4 meters, or 600 feet, so the base has dimensions of about 2225 km by 2225 km, or 1500 miles by 1500 miles. In the ancient Greek system of measurement, the base of the New Jerusalem would have been equal to 144 million square stadia.
In keeping with the several indications within Revelation text that there is some encryption, the cube may not even represent a cube, but rather a sphere or spheroid, with a radius equivalent to approximately 6,000 stadia or 750 miles; alternatively the symbol might be taken as a "sacred dodecahedron" with the twelve's given as a clue to its actual, faceted shape. Then the spheroidal pearl "gates" could be viewed as twelve satellites of a main structure or even a planetary system.
There are twelve gates in the wall oriented to the compass with three each on the east, north, south, and west sides. There is an angel at each gate, or gatehouse. These gates are each made of a single pearl, giving them the name of the ‘pearly gates’. The names of the twelve tribes of Israel are written on these gates.
The city’s wall has twelve foundation stones, and on them are written the names of the Twelve Apostles. The Bible does not list the names of the Twelve Apostles, and does not describe which name is inscribed on which foundation stone, or if all of the names are inscribed on all of the foundation stones, so that aspect of the arrangement is open to speculation. However, the layout of the foundation is precise with just one unique type of stone adorning each separate foundation stone.
This latter possibility is favored by tradition, as each gate presumably stands on one foundation stone, and each of the twelve tribes has long been associated with a certain type of precious stone. These historical connections go back to the time of Temple worship, when the same kinds of stones were set in the golden Breastlplate of the Ephod worn by the priest, and on the Ephod the names of each of the twelve tribes of Israel were inscribed on a particular type of stone.
For the author of Revelation, there is no need for a Temple because God will be the New Jerusalem’s eternal light and Jesus (the lamb) will be its lamp. This is further supported by the writings of Isaiah;
“Violence shall no more be heard in thy land, wasting nor destruction within thy borders; but thou shalt call thy walls Salvation, and thy gates Praise. The sun shall be no more thy light by day, neither for brightness shall the moon give light unto thee: but the Lord shall be unto thee an everlasting light: and thy God thy glory. Thy sun shall no more go down: neither shall thy moon withdraw itself: for the Lord shall be thine everlasting light, and the days of thy mourning shall be ended. Thy people also shall be all righteous; they shall inherit the land forever, the branch of my planting, the work of my hands, that I may be glorified.” (Isaiah 60 v 18-21)
There is no temple building in the New Jerusalem. God and the Lamb are the city's temple, since they alone are worthy of worship. Revelation chapter 22 goes on to describe a river of the water of life that flows down the middle of the great street of the city from the throne of God. The tree of life grows in the middle of this street and on either side of the river. Each tree bears twelve fruits, or kinds of fruits, and yields its fruit every month. According to John, ‘The leaves of the tree were for the healing of the nations.’ This inclusion of the tree of life in the New Jerusalem harkens back to the Garden of Eden.
John states that the New Jerusalem will be free of sin. The saints of God will have ‘His name written on their foreheads.’ Night will no longer fall, and the inhabitants of the city will ‘have need no lamp nor light of the sun, for the Lord God gives them light.’ John ends his account of the New Jerusalem by stressing its eternal nature;
‘Nothing impure will ever enter it, nor will anyone who does what is shameful or deceitful, but only those whose names are written in the lamb’s book of life.’ (Revelation 21 v 27)
And they shall reign forever and ever.