Stephen Biesty's books until I came across them again recently in the library. I had always loved pouring over their pages for interesting little subjects. His books feature freehand pen and watercolour cross sections with accurate and fine details. Some were historical (Rome, Ancient World, Stowaway) or informative - showing things you'd never usually see (Helicopters, Space Shuttles) but my favourites are the ones that show every day life (Castles, Subways) miniscule scenes with tiny people doing funny things. When I got home and checked him out online, I also found this absolutely stunning video:
Building Tower Bridge on Vimeo.