In an interesting twist, one major thing seems to be missing from many of these accurate statements about cities.
They seem to focus perhaps on european or US cities, in my opinion. Possibly some Chinese cities.

When you go through history about ancient cities, in so far as we accurately can, being that much of the history is myth [that many doubt] or supposition on the part of sociologists, anthropologists, and archaeologists, many cities seem to rest on the older ruins of another city. One which no one is certain why it was where it was. Though, many times there are reasons based on the ruling religion at the time of the original founding, or perhaps I would say ruling belief system. They may or may not have anything to do with the city in much of its later life. Due to that, they may bring material from ridiculously long distances away to begin the construction of some important structure. [Meaning they may, or may not, use local materials]
They may also take resources from an older city or monument to construct their newer one, as happens often enough.

As has been seen, cities may be built in what appears to be terrible locations. Sometimes this may be due to environmental changes over the long lifespan of a city, meaning it may not have been a bad spot when founded. Such that you may have what seems to be a city in a desert or in a very non-advantageous spot. Rising and lowering sea levels can lead to a city that seems to be an island near land in a way that seems impractical. Desertification is also a factor to consider.

Technological level does seem to play a significant role in what cities will be prominent in a given time period. Trains demonstrate this very well.
The advent of trains changed things dramatically as people could live further and in more varied locations, yet still commute to a larger urban center.
Travel times were greatly reduced and various options became available and changed how many businesses ran or where they were located relative to the urban center, like ice and live stock.

There are just so many factors leading to why any city looks the way it does.
I would definitely say it is always useful to have at least a basic little backstory for any city as it helps you understand something about why the city is and what its story is, the story that shaped why and where it is located.
The more accurate you want the city to be, the more information you will need for it, the surrounding area, the culture that started it, is there now, etc.

Or, you can just have fun and make some city maps.