Revelation 21:14-16

Young's Literal Translation

¹⁴ and the wall of the city had twelve foundations, and in them names of the twelve apostles of the Lamb.

¹⁵ And he who is speaking with me had a golden reed, that he may measure the city, and its gates, and its wall;

¹⁶ and the city lieth square, and the length of it is as great as the breadth; and he did measure the city with the reed -- furlongs twelve thousand; the length, and the breadth, and the height, of it are equal;