I think, based on what Waldronate and Korash have already said, you might want to check out the ancient Near East city of Catalhoyuk, in Anatolia. It was a city which didn't have streets (although it may have had shared courtyards. The buildings were built right up against each other, and access was through the roof. People could travel across the city by going (via ladders) from roof to roof. I can imagine this being used for your city (although, granted, it would be a challenge figuring out how to map it).