So, I had a hard time understanding what Minimalism is. So with google searches of what it is , I think I did this right. I wanted the definition of the buildings to stay but for the picture to look simple.

First I went to to colors » desaturate » lightness
then to colors » invert

I wanted to make sure it was dark enough so i went to to colors » brightness contrast » set it how i liked it

I then Colorized the picture

Then I grabbed the magic wand and made the background black, but left the moon filled with the foreground