They started off at very quick concepts. This one off how the bottom level could look similar to that of old London.
This again was a concept to just get an idea of what some buildings could look like. at one point the camera will be passing a close up of a building and this was an idea for that.
I also created a very rough camera shot in Maya with just blocks to get an idea of what is going to happen and how the city could work with the camera move.