City dwellers, there are a lot of things made more difficult by the urban environment, but puppy socialization is not one of them. The diverse and exciting world to which your puppy needs to be introduced is literally at your doorstep.
To properly socialize your puppy, you have to become curator and guide, with the goal of exposing your puppy to as many weird situations, noisy and crowded environments, diverse people, and varied dogs as possible… without also introducing feelings of fear or anxiety. You are laying the foundation for a behaviorally balanced, confident adult dog.
As your puppy grows older, she will, of course, be confronted with situations that are less than friendly or comfortable. She will encounter an aggressive dog, an unfriendly person, or a scary noise. But because she was properly socialized, she will be resilient and avoid getting any psychological scars.