Thanks again for the feedback guys. Marcus, I have MultiMarker and its a fantastic tool, but I didn't use it for these images.
I basically created a load of different tools, set up a cube in an 'isometric' position on a seperate layer, and used its sides to draw tonnes and tonnes of structures, trying to keep the rotations within the isometric parameters.
Here's the latest WIP, went crazy in Photoshop with these renders - as you all know, often what you start out trying to create disappears and you end up with something you weren't expecting!
My site's down at the moment, will post higher-res views tomorrow if people fancy a look.
Hope you're all well,
Phil