All other Cities in the world seem dull after I saw X City?
Have you ever seen a City in your travels around the world that just put everything else in the dust and set the standard? This City may have been dirty, dark, smoggy, or poverty filled, (or beautiful) but was just so interesting and exotic that all other places seemed dull in comparison. Maybe it is something off the beaten path, or out of the traditional tourist loop, but still welcoming to outsiders.
What is the most stimulating and interesting City on earth for a traveler?