Freeport

No, not that Freeport.  Well, actually kind of.

The primary port and largest settlement of the Shieldlands is Freeport, located at the mouth of the Tongue.  It's a lawless, pirate town without much in the way of government; technically there's a mayor, one Redjack, but he's a retired pirate himself and there's not a whole lot of power that comes with the office.  The remnants of his crew make up a nominal police force, but...  they're pirates.  People, including thieves and cultists, mostly do as they please, and a body in the gutter is by no means an uncommon sight.  Naturally, this makes the place somewhat popular with merchants moving questionable merchandise, provided they can provide for their own protection.

Freeport was not always so free.

Before the Zaharan cataclysm, Freeport was the seat of the merciless House of Nacht.  The nearest humans to Zahar, they paid tribute to it and worship to its gods, and were greatly favored, to the point of marrying into the Zaharan nobility.  In time, their sorcery grew strong enough that they raised a castle of solid black stone from the earth beneath Freeport itself, and in the labyrinthine catacombs beneath it they performed rituals most foul.  When the Zaharan War came, they stood with the Zaharans, and paid the price.  It is unknown whether any survived, but their legacy remains in the looming form of Castle Nacht over Freeport Harbor.  The castle is now thoroughly haunted; pirates and cultists alike go in, seeking forgotten treasures and ancient knowledge, and those that come out tell terrible tales of the walking dead and fouler things.  Their stories are occasionally verified when things that were imprisoned in the bowels of the castle get out into town...  [Meta note - I'm looking to make the basements of Castle Nacht a smallish megadungeon type thing.  In due time.]

It is well known that several chaos cults to the myriad chaotic powers are active in the seedy underbelly of Freeport, but which ones are anyone's guess.  Cults come and go in an ideologically-consistent random fashion.  Fortunately, much of their scheming is directed against each other, though the city's poor often feel the sting of their sacrificial blades.  It is unknown whether there is something in the Castle that draws cultists naturally, or if at this point it's just an established cultural institution.  No significant outside force has attempted to eradicate the cults with any success since the War, though individuals have certainly carried out bloody vendettas against individual cells, which are soon replaced.

Caravans through Freeport are highly uncommon; to the south lies blistering desert, and while to the north are festering mires.  Riverine and sea travel are about the only ways into and out of the city.  Boats traveling upriver are most often headed up the north fork to Deal and Ironbridge, while ships out the bay are usually bound for Dardantus or Soros.  Small coastal schooners occasionally run north to Fishtrap (though the rumors of that place are fell), and to Myrmidia beyond.  Most reputable merchant cartels avoid moving cargo through Freeport, leaving that risky business to independent captains.

In short: as dangerous a city as they come...  but a class II market, which means you might actually be able to buy or sell permanent magic items there.