The trick to achieving verisimilitude when depicting a fictional city is to follow the path from Vikram Chandra to Michael Chabon to China Mieville. All three share a certain approach when it comes to world building, in that they inhabit their setting so completely that they’re able to convey an incredibly immersive description that makes the city feel palpable. Chandra describes the real Bombay in our world, Chabon describes a fictional Sitka in Alaska, and Mieville describes a fictional New Crobuzon in his fictional world. Each is one step removed from the other, but by using the same techniques (and wielding no small measure of genius) is able to make their cities as real as can be.
What is this method? It’s the ability to intimate at a city beyond the scope of the narrative. At making you feel as if there are streets leading off from every avenue the characters walk and drive down, each as real as that which is being described, filled with a life and momentum of its own.
This is accomplished in several ways.
One is to assert the greater complexity of your city by referencing out of sight facets in casual, non-intrusive manner. So your character might be walking down a street and smell the fish cannery a few blocks over. Or there might be a poster of a local religious leader on the wall of a clerk’s office that you name by name. Or the newspaper might mention a local strike on the other side of the city, or your character might ride a taxi-cab past a picket line. All of these hint at out-of-sight industries, economics and religious activities that fall outside the scope of your novel but which hint at a greater life at play within your city.
More thoughts on this anon.