Originally Posted by
Puffin
I've never built cities before, I've only destroyed them. xD I might try this.
If you build a city in one dream, there's a good chance it won't show up again in non-lucids unless you constantly think about it during the day... Even so, it won't look the same as it did in the previous dream; that's just how dreams work. Because of that, it probably won't be too effective as a dream sign. Once you're lucid though, you can definitely summon it again and have it look fairly similar; if you visualize it well, that is. :)