I suppose every medieval port will be different, and hopefully this doesn't veer into example-seeking, but certainly they all had harbours for ships (a big enough port would have quays for the smallest craft to the largest galleons), and warehouses to store imports and exports. And of course, as you mentioned, there would have been offices to handle all the paperwork and bureaucracy.

The one I know best is the port of Acre, when it was the capital of the crusader Kingdom of Jerusalem in the 13th century. Hopefully this will give you an idea of the typical buildings of a port, although of course in many ways, as a European outpost in the Near East, Acre is also non-typical…

Acre is located at the north end of the Bay of Haifa. Haifa itself is at the southern end, about 20 km away, and it has the bigger and better port today, but in the Middle Ages, Acre was much better suited for large-scale maritime trade. The port is on a small promontory extending south into the bay, so it sort of looks like a little hook hanging off the mainland. At the very end of this promontory, the walls of city extended to the east out into the bay, a fortified mole or breakwater (the “southern breakwater”). There was another fortified breakwater extending down into the bay from the northern part of the city walls (the “eastern breakwater”), and at the end of that one was the Tower of Flies, which was also fortified, and could also be used as a lighthouse.

Ships entered the port between the two breakwaters, but there was a big metal chain there blocking the entrance, which could be lowered to allow ships to pass through. I’m actually not sure how typical a big chain was, but Constantinople had one as well. In Constantinople it blocked from the Golden Horn (on the north side of the city) from the rest of the Bosporus to the east, and protected all the commercial shipping areas in the Horn. In Acre of course it was much, much smaller.

Some of the major maritime cities in Europe established trade colonies in Acre and other crusader cities. Venice, Genoa, and Pisa were the main colonies in Acre and their neighbourhoods all had facilities in this pool behind the chain. They actually called this “neighbourhood of the chain”, since the chain in the bay became a symbol of the whole port area. The main building there was the “court of the chain”, which was a huge market (a “fondaco” in Italian, or a “funduq” or “khan” in Arabic), but it was also a legal court where commercial disputes could be heard. So if someone claimed that a merchant was using improper scales, or someone had forged documents or defrauded another merchant, or for theft or assault or other relatively minor crimes like that, there was a tribunal to deal with them.

Due to the multicultural and multilingual nature of crusader Acre, the court of the chain (the market and the legal court) was presided over by a mixture of Latin European Christians (representing the crusader government and the Italian city-states) and native eastern Christians. The official in charge of inspecting the markets and maintaining order was the “mathesep”, which is the way the crusaders pronounced the Arabic word “muhtasib”. The marketplace was also full of interpreters, translators, money-changers, and in the 13th century there were lots of Italian notaries. They could settle minor contracts or disputes between merchants coming and going in the port without taking up the time and resources of the market court (although for disputes that were worth more than a certain amount of money, or for violent crimes, the regular courts had jurisdiction). All of these people would have had offices or at least stalls in the “court of the chain”.

The Venetians, Pisans, and Genoans had their own markets as well, warehouses, and maybe their own quays where their own ships could dock. They had their own local neighbourhood churches and fortified towers. Beyond their neighbourhoods was the rest of the city - the Templar and Hospitaller fortresses, the cathedral, the residences of the Bishop of Acre and the Patriarch of Jerusalem, the royal palace, etc., and then beyond the city walls there was the unfortified suburb of Montmusard. Further beyond that would be farmland and sugarcane plantations, which were sometimes owned by the Italian merchants. Beyond the territory controlled by the crusaders was Muslim territory, and although there was sometimes warfare between them and those areas were unsafe, most of the time they were full of Muslim merchants travelling into the city or crusader/Italian merchants taking their own goods out the other way, north to Tyre or Beirut or south to Jaffa (also crusader cities) or east to Damascus and the rest of Syria.

One thing that Acre apparently did *not* have was a dry-dock or shipbuilding facilities. The crusaders didn’t really have a navy, and if ships needed to be repaired, they would have to go to Tyre. Unfortunately I don’t have this same amount of information at hand for the port of Tyre but it seems that that’s where the dry-dock was.

Hopefully that gives you an idea of a busy multicultural port! I wish I had more info about Constantinople and Tyre. Ports elsewhere in medieval Europe might differ in the details but they would probably seem generally similar.

Sources:

David Jacoby, “Crusader Acre in the thirteenth century: urban layout and topography”, in Studi Medievali 20 (1979)

Ruthy Gertwagen, “The crusader port of Acre: layout and problems of maintenance”, in Autour de la Première Croisade, ed. Michel Balard (1996)