As with any major project it is always best to start from the ground up, thus to build an entire gaming world we start at it's smallest part. So for the DM this is the first focal point. Here is the quickest and easiest way to build a city (town or village, on a smaller scale) that I use.

1) Get a large sheet of paper or poster board (found in any Wal-Mart store) and with a yellow highlighter marker make intersecting lines, these are your roads. Have areas of neat squares and other areas of tightly convening lines, these are your city's upper and lower class districts. Not all the lines need to connect...dead end streets. Don't forget to have roads leading off the page to show routes to the outside world and keep a large central area open for the Castle or Seat-of-Government...also large areas if you want coliseums, marketplaces, cemeteries, etc.

2) With a pen draw a small square next to one of the roads the size of a common house. This you use to show scale to the rest of the buildings.

3) Get a phonebook, pen, and paper. Write down all the different occupations that are contained in the yellow pages. Next to them right down their medieval equivalent...most will transfer over as the same: carpenter-carpenter, mason-mason, doctor-physician, etc. Others you will have to use your imagination; electrician-light stone dealer (the local magic guilds will have shops selling marbles with continuous light spells cast on them- a magical world's version of light bulbs).

4) On other sheets of paper write down the fantasy versions and after it a store/shop name; Mason-Grodius Stoneworkers, lawyer-Reginali Legal Services, etc (Remember that with most of them there should be more than one of each). Now add to the list stables, Guild Houses for the different occupations, warehouses, Temples to your gods, and any other AD&D used buildings. After the list is done, number them down the page(s).

5) Decide where in your city each business/building will go, make a building shape to scale there, and put it's corresponding number into it. After (or while) this is done make buildings for the castle, barracks, dignitaries, guard houses, etc (Governmental). These you can label with a, b, c, and d.... Transfer the letters to paper with building titles like above. (Don’t put in secret locations like thief's guilds...)

6) Now fill in the rest of the map with empty building shapes...these are the residential houses. If your city is walled, put the wall around it in large marker, leaving an opening at the outgoing roads (these are your gates). In a Port city don't forget to show the coastline and drawings of docks (also put more warehouses here). Name your streets and roads.

The birth of a city can be caused by a number of different circumstances: growing around a fortified keep or castle, a crossroad of commerce, from the shores of a deep and secure port, etc. Cities don't grow in a vacuum. An element of some kind causes the village to grow.

The first stage is the Village: A gathering of families in a setting for common protection. The closeness of the community’s resources allows its growth to begin. This can be farms, lumber, good fishing, etc. It will have only the barest amount of support services like a tavern and blacksmith.

The second stage is the Town: This only happens if a major element is found or established in or near the village. Such things include a mining operation, a trade route, military camp, shipping (if on coast), factory, and others. As 'settlers' come to the city to work within its element others come as advance supporting services like entertainment, inns, repair shops, education, religion, social, political, law enforcement, etc.

Then the third stage Minor City: As the population increases the initial element gets push back until the bustle of the city takes on a life of its own. Other elements are transferred or begin here just for the reason that there is already a foundation; labor, support, protection of law, and order. These new elements bring with them other supporting factions, helping its rise.

The fourth stage Major City: With multiple elements, all working at peak levels and new ones still joining, the growth of the city is from its own population and not from the transmigration of outside peoples. The best clue as to when a city has reached this level is when; unemployment starts to rise rapidly, increase in crime, growth of homelessness, etc. The city can't support its population fully.

Kingdoms will be made up of a combination of the various stages. In designing a city one must determine it present stage and place in it the appropriate numbers of resources, elements, supporting services, and population size. Pick the city's major element(s) and include on your map, and within the key, the needed buildings, networks, usable land, and storage facilities. The element(s) will give you an idea as to what a large portion of the city's population earns its living from, thus their jobs. (A city involved in shipping will have a lot more shipwrights, carpenters, dock workers, sailors, etc then an agricultural city of farmers, ranchers, and grain merchants.) This should help in filling out the city's population...and what 'types' the characters will meet and buildings they will find.

Capitol cities can have the same growth experience, from village to major city, and thus will have its own major element(s). Unless the city was built from scratch to be the capitol and this would then make its major element Government. Populated by bureaucratic offices, courthouses, nobles and court members' estates, and royal functionaries (Palace, royal guard barracks, etc). Note: Planned cities will have a more uniformed street and building plan.

After you have finished the rough draft on your city map, you can then pick the major and minor element(s)...Keep in mind that major elements are the main focus of the city's industry and larger cities can have more than one. Minor elements are those industries that 'feed' off of the major elements, employing less of a labor force but are more skilled and specialized (Major- Stone quarry...Minors- Stone cutters, sculptors, construction, teamsters, etc)

Here is a copy from my list:

Major Elements: Agricultural*, shipping port, stone or marble quarry, ore-mineral-gem mines**, military post or fort, government, trade, heavy lumber industry, exotics (silk, lacquer, fruits, porcelains, etc), tar/oil (whale, animal, or ground), chemicals (dye, perfume, soap, etc), and recreation (resort, beach, waterfall, etc).
* Note- agricultural can be one or several of the following; grains (corn, wheat, rice, etc), vegetables, cattle, sheep, pigs, horses, cotton, hemp, spices, herbs, fish, and sugar.
** Includes-gold, silver, copper, iron, tin, diamonds, rubies (and all other precious gems), coal, lead, amber, salt, sand (glass), and lime.

Minor Elements; Bakery, brewery, grain storage, livestock processing, wool, leather, jewelers, armor, weapons, brass, bronze, shipyard, shipwrights, sail cloth, textiles, utensils, pottery, glassware, dishware, furnace/smelter plants, stone cutters, sculptors, construction, teamsters, porters, slaves, and the list goes on and on, but you get the idea.

Once you have chosen the Major and Minor elements sketch the appropriate buildings and such into your map. Now you are ready to start your Encyclopedia of your world. Keep this in mind...the items I will be going over will not be in the order that they may appear in your 'book'. Just doing it this way helps in keeping your mind focused on the overall picture.
DO ONE CITY AT A TIME! This insures the continuity and concepts of the city...preventing contradictions.

A city is like a living organism and like all life it has its own abilities and needs. The city has its own strengths and weaknesses. So now that you have your city map and elements we can start writing down the stuff that make this city unique.
(It wouldn't look good to label the sections in your Campaign World Notebooks as I have done; I just wanted to show you where I was basing my thoughts on.)

STRENGTH: Describe the military aspects of the city, including the city guard. The guard's choice of weapons, armor, cavalry, uniforms, etc is important items to include in this description. Give rough estimates on numbers and combat skills. Tell of their leaders, fortifications, training, and such that would give players an idea of the city's defensive and offensive capabilities.

INTELLIGENCE/WISDOM: Breakdown the city's education format; schools for children, colleges, trade schools, specialized training centers and/or magic academies and religious seminars (if the city has any or all of them). Libraries, archives, and noted scholars can also be noted.

CHARISMA: Describe in words the look of the city as to its architecture and layout...does it have grand flowing stonework or clusters of clay brick duplexes? Wide-straight streets or meandering narrow avenues? Give the players a sense of its beauty or ugliness. Even tell of the difference in the various 'boroughs' of the city.

CONSTITUTION: Tell of the health and/or sickliness of the general population...are they strapping young men and women or suffer from malnutrition and war? The city as a whole, tell of its past...is it new or an ancient site, has it been sacked and rebuilt, is it in decline or rising to glory quickly?

DEXTERITY: The pace of the city. Is it bustling with activity or quiet and laid back? Do they take quickly to strangers (constant flow of foreigners) or are suspicious (an out-of-the-way place)? Hectic Rome or mellow Venice?

FOOD: All cities have access to food supplies and water sources, or they wouldn't exist, and they don't need to be an Agriculture element Power Base (discussed later). They get it from the surrounding villages, other cities, and oversea shipping. At this point you can just list where they get it, even naming places that you haven't created yet...you'll get their. Plus by mentioning these other places you will slowly start fusing the world together as you build each city in its turn.

EQUIPMENT: The list would be too long to mention everything the city has to offer, instead describe those things it lacks and why. Ex: 'Since the assassination of the Duke's son a banned has been put on crossbows, and even holders of bows are met with suspicion.' OR 'Due to the embargo laid down by the King of White Pearl for city Alpha's collaboration with the Ilyamus uprising, fruit shipments are non-existing.'

RACE/CLASS: A breakdown of its population. Include the percentage of non-human inhabitants, even a census of various human 'races', as in the real world (numbers of Germans, Italians, etc living in France). This could be added to this section after the history of your world has been completed and you therefore have an idea as to what races may have 'shared' this city.

*******After completing these four sections on your first city, go back, and start the next. Do all your cities first and don't think about Kingdoms yet. My reason for this is that if you formed a kingdom first then all the cities you create in it, they may start to look like. And as no kingdom started from scratch, with all their cities pre-made, this similarity wouldn't happen. Each city was at one time a city-state; all by its self and only through conquest was kingdoms formed. Building the cities first, as individuals, and then placing them in a kingdom will give you the feel of a medieval kingdom. So decide how many cities you want in your world (including the ones you may already have fleshed out from previous games, groups, modules, etc) and build them all first. NOT villages, they came later as the support of your cities.