As I planned to create the entire city from one sample I first removed the parts which would be most noticeable when duplicated i.e. larger lights and the lit, distinctive architectural features.
I filled the gaps using Content Aware fill, then used several copies of this layer to build up enough image to work with in the next step.
Here I made the image more dynamic by using duplicated layers set to Overlay blend mode.
I added colour to the main image to help it seem part of the overall environment by using a duplicate layer of the background set to Overlay at 19% opacity.
Chopped train in half, duplicated, darkened, and colour-matched to main image.
Liquified top 'rim' of the main image to create depression, and darkened to add a sense of depth. I also added some shadow and highlights to the 'centerpiece'.