An epic project, no mistake, and how - watching it progress is amazing.
May I ask how exactly you 'work' the polystyrene? I always try and avoid it, since i've seen how it can look tacky and ruin scenery/dioramas when done badly, but your cobble streets and brickwork are amazing.
Think i'll start my own diorama adventures much more smallscale (read: msondter-base size). Sadly I don't have any room in my home for anything so epic, or to work on it for that matter.