There are plenty of "medieval" "cities" out there. Only half of them are medieval and the rest are ether fantasy or renaissance. The medieval period lasted from after the fall of Rome (500AD) to the fall of the Ro- er... Byzantium Empire in 1453AD. So what was in this period?

-Castles
-The Vikings.
-The Bulgarians.
-The Byzantines
-The English and French
-Other, miscellaneous European kingdoms.
-Longswords and many other medieval weapons.

Not Medieval:

-Cathedrals and Palaces.
-Coffee
-Firearms.
-Forts.
-Navigation.

I commonly see someones medieval city with a cathedral and/or palace. Cathedrals and Palaces were renaissance and not medieval. Medieval had more basic churches and (my personal favorite) castles. In the 1500's, castles became obsolete and were replaced by palaces and forts. And of course, the introduction of cathedrals. Now that you know the basics of what is and isn't medieval, lets move on to my next point:

Cities! Or not...

Many people made a "city" and made the mistake of calling it that. A lot of "cities" here on PMC are tiny. Like town size. The Absolute minimum population for a city would be about 1500 over a square kilometer (1000 square blocks) and having a downtown area (for the medieval period). I like to measure population in number of beds. A lot of peoples cities look like they have 50 to 100 people (large village) despite their "city" having a "city look and feel". This is badly unrealistic because these "cities" are under supported assuming that they are real. My own Tasvir has a population of about 700, at a guess and a downtown area, putting it at half way to city status, making it a relatively large town. Lastly, though it isn't a requirement, density. Typically, cities will be incredibly dense inside the walls and spread out outside the walls.

I hope this cleared a lot of confusion (or possibly created some along the way) or at least taught you something about history.

Tasvir: www.planetminecraft.com/project/tasvir/