"A great city is, to be sure, the school for studying life."
— Samuel Johnson
The city. Urbs. Civitas. Polis. There is something powerful about the packing of places and teeming of characters that make it rich for the imagination to inhabit. Thus it is one of the settings that I love, even for fantasy adventure. It's not because I eschew variety: the hamlet, the wilderness, and -- especially the Underworld -- all have their charms. But a well-drawn city matches the well-done Underworld in my book. Dickens' London (to choose one London), lives for me and it is one of the Londons that I love; Rutherford's is another. McCullough's late Republican/early Imperial Rome likewise seems a real place with its own distinctive character. I'd like to find fiction set in Venice and Florence that do the same for those cities in the Renaissance. It's been a long time since I read much Ann Rice, but I think I'd probably say her New Orleans, and perhaps to a lesser extent her Paris, read well. The Thieves World novels made Sanctuary breathe and roar and spit. In game settings, the Free City of Greyhawk, Waterdeep, and Golarion's Absalom (for sale here) are intriguing cities that promise strong sense of place. 
What cities do you love? What materials from fiction or gaming deliver a city in its stones and in its soul to your imagination? What are the touches that make the city seem a unique, living place? Are there equivalences of the double decker bus, the little black cab, the red phone box, and the red royal post box? How do you go about city building in your secondary creations? I would love to hear your thoughts, examples, and recommendations!