In a lot of modern fantasy worlds that are roughly based on a Medieval setting, cities have concise districts. In Magic: The Gathering's Thraben, you've got a city that has multiple sectors partly defined by the layers of walls around them: the Merchant's Wall, for example. In World of Warcraft, you've got cities like Stormwind and Undercity with large, defined chunks like the "Trade Quarter" and the "Military Quarter." But what about in real-life cities?
My uneducated impression, of, say, late Medieval London, is that it began when a community of primitive houses started producing specialists in trade and became interdependent, expanded out with more and more services, and eventually became somewhat of a mess except for a few sections that had an obviously distinct purpose such as the executive center and places that were involved in crop production. However, I have no idea if this is correct.
Did kings and rulers and councils in that area and age tend to organize cities in a way where you could say "ah, this is where the weapons dealers are," for example, perhaps with the armor-dealers and toolsmiths right across the street to form a 'blacksmith's sector,' or were there a variety of shops selling almost anything scattered throughout a large city?
How strong was city-planning and district-designating in general in the Western European Medieval world? Did this change over time or vary significantly from country to country or city to city? If it did exist, how did this city-structure take its form over time?
Did kings and rulers and councils in that area and age tend to organize cities in a way where you could say "ah, this is where the weapons dealers are," for example, perhaps with the armor-dealers and toolsmiths right across the street to form a 'blacksmith's sector,' or were there a variety of shops selling almost anything scattered throughout a large city?
How strong was city-planning and district-designating in general in the Western European Medieval world? Did this change over time or vary significantly from country to country or city to city? If it did exist, how did this city-structure take its form over time?
In al-Andalus, especially with newer developments, cities were often well-planned. A particularly good example of this is with Madinat al-Zahra, one of the most important cities in western europe in the 10th century. Nowadays it is an extensive set of ruins, but in its day it was a legendary capital of al-Andalus (located by D. Fairchild Ruggles about 7km west of Cordoba, Spain now), built during the reign of Abdul Rahman III. Here's a cool thing I always liked about Maribel Fierro even notes that there was an specially built tank of mercury in the hall that was built in such a way that the light would shine into the hall and bounce around, causing the mercury to sparkle. When he wanted to impress visitors, Abdul Rahman III would give a signal to people in the palace to operate a mechanism that made the tank vibrate - Ruggles also refers to this, translating a cool bit from original text: "whereupon there would appear in the chamber a flash like that of lightning bolts that would fill the hearts with fear".
Anyway, cool anecdotes aside, back to the actual question. So Madinat al-Zahra was very carefully planned. Around 940CE was when construction commenced, and it was to be a royal city occupying the role of a "dual capital" with Cordoba - that is, they weren't intended to be rival cities, but to complement one another. Madinat al-Zahra was a completely self-sufficient city with mosques, markets, baths, bureaucrats, everything a Western European medieval capital city would need. Basically, the layout of Madinat al-Zahra was like this: A series of terraces, with three primary large, stepped terraces cut out of the slope of a mountainside. The upper terrace was dedicated to residential buildings. The middle terrace was where you found all the official buildings, as well as some large, open gardens with fruit, flowers, etc. The lower terrace contained places where crafting and manufacturing of various things like pottery would take place. There was a large mosque in a lower terrace outside the walls. Notably, Fierro points out that Madinat al-Zahra is marked by Eastern Roman/Byzantine influence in its architectural elements and decorative motifs, suggesting that their city planning & design might have been influenced somewhat by architects from Constantinople. Additionally a lot of the design of the city was to allow for panoramic views and vistas of the surrounding regions.
The aesthetic aspects of city planning in al-andalus during this period were meticulously designed, too. The design & materials of the town were noted to be particularly white by a slave to the Caliph, so the trees in the area were all cut down and replaced by fig and almond trees so that they added the whiteness of their flowers to the whiteness of the town when they blossomed in springtime (Fierro). The flowers & fruits in the gardens were designed to reflect a Quran verse (55:46-78) that described two dark green gardens, with two flowing springs, pairs of every fruit, flowers, trees, etc.
So in the case of a place like Madinat al-Zahra, there were definitely cities where you could say - "this is where pottery is made, this is where the nobles live, this is where people grow flowers and an orchard is across the street". In al-Andalus there's a variety of examples of planned development like this. That said, there's just as many examples of things being chaotic and mazelike. Sometimes cities and palaces were built to impress rivals or proclaim superiority in a way over others, so it's worth remembering that when using an example like Madinat al-Zahra because it was built partly to show how developed and wealthy the Andalusi people were, especially in comparison to northern and eastern rivals. So it definitely varied from city to city, and over time. At least in al-Andalus. I would say for the purposes of fantasy worlds, having some cities that are well-planned into districts is realistic, but all of them? Certainly not.
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Hi there! Sorry I'm late to this thread, but if you're still interested, I can offer some insight on medieval city planning.
Firstly, most Western European cities can trace their roots to the Roman Empire. London may have started out as a "community of primitive houses"; but the expansion of the city under the Roman Empire would have enlarged it to the rectilinear City of London we know of today (that is to say, the area literally called as the City of London which encompasses the modern city's financial district, excluding Westminster and the rest of the modern metropolis). The Museum of London has a really cool map you can look at where you can see many typically Roman urban characteristics: two diagonal arteries crossing a (roughly) rectilinear plan of streets, with a Forum (marketplace) more or less at the center. Most roman cities were, like London, a mix of perviously existing characteristics and Roman planning.
Massive public works and planning on the scale of the Romans wouldn't be seen again in the west at least until the 18th-19th centuries (in some countries even later, to cite London again, city planning was always particularly troublesome in England because of the particularly strong laws protecting private property, making necessary relocations and demolitions nearly impossible) but the Middle ages did see some limited city planning.
One of my favorite examples of haphazard but functional city planning is Venice. In 1291, the administration of Doge Pietro Gardenigo had enough of the city's glassmarkers' furnaces starting troublesome fires, and promptly had them all move them all to the nearby island of Murano, which promptly became a vibrant center of glassmaking, still active to this day. Not much later, a ruling was made to move all tanners (leatherworkers) to the nearby island of Giudecca (tanning is a very smelly business). Specific streets of the city itself were also reserved for different professions, sometimes for taxation or regulation purposes, while sometimes people with similar professions just found it more convenient to live closer. The status of Venice as the largest commercial center in Europe can readily be seen in the names of these streets, bridges, and canals.
Although the professions tied to them have long since moved away, pulling up a map of Venice I've found you can still find the Ponte dei Chiodi ("Bridge of Nails" which leads to the street where all the nail makers were) Ponte de le Erbe ("Bridge of the Herbs" denoting the district where apothecaries and herbalists worked) Ponte dei Lustaferi (I think this means "Bridge of the Lightmakers" denoting candlemakers) Ponte dei Fuseri ("Bridge of the "Fuse-Makers" I think) Ponte della Fava (leading to where the fig importers could be found) Ponte dei Scudi ("Bride of the Sheilds") Ponte dei Tabacchi ("Tobacco Bridge") Ponte delle Tette ("Bridge of Boobs" where you could find, ehm... you can imagine) along with various ethnic enclaves for foreign merchants who came to the city for business and trade; Ponte e Rio dei Greci ("Bridge -and bank- of the Greeks" denoting the Greek Quarter) Fontego dei Turchi (a cross between a hostel and warehouse to house the Turkish merchants) Fontego dei Tedeschi (a similar building for Germans).
There is also a quarter called Castello, or "Castle": here, not only was there once a castle at the city's easternmost tip, but the vast majority of the quarter was either inhabited by soldiers or people employed by the Arsenal, or the state-run military shipyards and foundry, perhaps the closest thing to a "Military Quarter" like you mentioned in your original question (as for a trade quarter though, that's much more difficult. People in cities don't farm, so by exclusion, they partake in commerce. Much like in modern cities, trade happens all over the place, everywhere and all the time. It's just what people do).
At least in Italy, many cities had at least some streets set aside for specific professions. Milan, for example, despite it's massive restructuring and rebuilding, still has streets in the city center named Via Orefici ("Jewler's Street") Via Armorai ("Armorers Street") Via Spadari ("Sword-smiths Street") as well as Via Zecca ("Mint Street", where coins were minted) and Piazza Mercanti ("Merchant's Square" where the market was held). However, today very little of these streets' original character remains.
There's a whole discussion we could have about the flow of people (specifically, angry people) in cities and urban planning with regards to road (and waterway!) construction, where I could really go on for ages. But that's a discussion for another time.
TL;DR Some, very specific city planning did occur, mostly to stop fires or better regulate some industries. Some cities had lots of planning, other cities had minimal planning. Many medieval towns had no planning at all. And if it was important in the middle ages and is still important today, even if there was city planning, it's probably unrecognizable today.
