I think that one advantage to building on a world scale is that you can take a city's present day layout and work backwards through its history based on the geography you've already created. Mind you, this is if you don't already have a complete history thought up for the city. For instance, let's say you've made your continents, calculated where the mountains go, and figured out the courses of your rivers. For a certain city:
Does it lie on an island situated in a major shipping lane? If so, it's going to be rich from trade, tribute, and knowledge.
Does it lie at the mouth of a great river? If so, it will be a major port and a gateway to the sea via ships, and to the interior of the continent via barges.
Is it near a dormant volcano? Then it was probably destroyed at least once in recorded history.
Is it near an active fault? Depending on the type of fault, as with the volcano, it's probably been destroyed at least once in the last few hundred years.
Is it in an open plain or desert in the middle of a continent? If the passage through is more East/West, a greater flow of trade and knowledge will occur. If the general passage is North/South, the change in climate usually hinders trade somewhat.
Is it high in the mountains or beyond a formidable mountain range? Then to a greater or lesser degree, it will be isolated, provincial, wary of outsiders, and resistant to change.
Is it near the ocean? Even if it's not a major port, a seagoing city gets its food from the sea and makes its livelihood from the sea.
Is it near a large lake? Provided the lake's water is not brackish, the normally ongoing quest to bring fresh water into the city from afar would not be a problem and resources could be channeled elsewhere.

Each of these things, and the conditions they produce, dictate the size, architecture, art, design, and many more aspects of a city. Lastly, a city's location, unless it's a modern new city, will probably be near a river, a lake, a bay, or a natural harbor like Hong Kong or San Francisco