Revelation 21:16

An Understandable Version (2005 edition)

Now the city is laid out as a perfect square; its length is the same as its width. So, he measured the city with the stick [and found it to be] fifteen hundred miles each way; its length and width and height all being the same.

Cross References

Revelation 21:15

And the angel who spoke to me [See verse 9] had a golden measuring stick with which to measure the city, its gates and its wall.

Revelation 21:17

And he measured its wall [and found it to be] two hundred and sixteen feet [high], according to human measurements which the angel was using.