It is striking that each of the other three vignettes begins with a reference to the angel who showed John around (Revelation 21:9, Revelation 21:15; Revelation 22:1). That John omits a reference to the angel at the beginning of the present scene may perhaps best be explained by the amazement John experienced at what he missed (while the angel was measuring the city and pointing out the wonderful stones and the glorious gates and the abundance of gold) and now records: the city has no temple!
22 And I saw no temple in the city, for its temple is the Lord God the Almighty and the Lamb.