Had a golden reed to measure the city. See Barnes on "Re 11:1".

The reed, or measuring rod, here, is of gold, because all about the city is of the most rich and costly materials. The rod is thus suited to the personage who uses it, and to the occasion. Compare a similar description in Eze 40:3-5; 43:16. The object of this measuring is to show that the city has proper architectural proportions.

And the gates thereof, etc. To measure every part of the city, and to ascertain its exact dimensions.

{p} "golden reed" Re 21:1; Eze 40:3; Zec 2:1