Revelation 21:17 records the measurements of the new city. The wall was measured by human measurement, which is also an angel’s measurement. Verses 24 to 26 mentions about the nations bringing their glory into New Jerusalem. It also talks about the sun, the moon, day and night in the new heaven and new earth. In the city, there is the throne of God and of the Lamb, as well as the tree of life and the river of the water of life. All these let us know that New Jerusalem is not a symbol, nor is it the church. It is a real physical city.