There are places in the world that are not recommended for tourists.
This city is well placed at a spot several major rivers flow out into the sea, built on the coast and stretching out to the hundreds of small nearby islands with a network of spiderweb-like bridges. The weather is temperate and calm, and this part of the coast rarely sees large storms or hurricanes. On one of the larger islands, a tall castle stretches up towards the sky, striking and dramatic against the horizon. Lush green ivy climbs delicately up its shining white walls, contrasting well with the red-orange of the tiled roof that caps its spires. It would be picturesque, but for the long and glittering silver thorns poking out from the ivy, the pale and thin scars of claws that scratch down the white brick, the crumbling, abandoned ruins of the city that once surrounded it.
But really, the major sticking point for why it's not a good destination for tourists, even getting past the deadly monsters, is that an hour spent inside the borders of the cursed city might become a week, a month, or even a year or two on the outside.
Spend longer, and there's no telling how long it could be.