Again another verse.
Revelation 21:24 And the nations of them which are saved shall walk in the light of it: and the kings of the earth do bring their glory and honour into it.
Isaiah 60:3 And the Gentiles shall come to thy light, and kings to the brightness of thy rising.
If the kings and "aliens" (As you call them.) bring their glory into the city, then they will probably build your walls with precious stones.