Nidus - The Shifting City

So, I last left my daring players looking for a town. My initial thought was to make some small medievalesque town they could travel to, just big enough to get rid of their loot. But what I immediately became obsessed with was something completely different.

Once, I ran across a picture of a real town in a book that grabbed my brain and transported me. I think it was in Italy or Greece, it showed an old town with stairways leading to doors and a door under the stairs and another set of stairs going a different way, leading to a different door. Doors and stairs. It was like a urban labyrinth. Aha, I thought, what if a whole city was like how I imagined the Tenderloin of Lankhmar or the Maze, in the Sanctuary of Thieves' World to be. Something unmappable, unknowable, dangerous territory.

This is not the same picture,

but similar. The city is not just a maze in two dimensions, it's a nest of stairs and passages, doors and plazas. It is carved from stone and whitewashed. And it is on a tiny island.

Nidus, City of Pirates, City of Thieves, City of Lost Things, of cultists and heretics. The shops and lodging places shift constantly, those doing poorly forced to smaller holes-in-the-walls, those thriving taking over plazas. No one is in charge. No thieves' guild, no demon, no great mage. Nidus, City of Uncertainty.

In my mind it is a visual amalgam of the troglodyte houses of Matmata, Tunis:


the Greek isles of Santorini:


And Elkep Evi in Turkey:


My post about dicey lodgings was my first attempt at embodying this location in rules. But how do I convey this teeming white maze of doors and stairs to my players?