Chicago always seemed unknowably vast to me. I can navigate within it, but I don't think I ever really knew any area of it other than Hyde Park. San Francisco is the only place larger than a neighborhood that I've ever felt like I actually knew.

But by the can-you-navigate-without-a-map standard:

1. San Francisco
2. Oakland
3. Berkeley
4. Chicago
5. Indianapolis

and that's probably about it.