Sewer Cross-Sections & Dungeons

I've been thinking a lot about sewers this month. I continue to plug-away at Dungeon 23, and August's level is a section of sewers from Myr Regath, the city that is now a megadungeon. My long-running story game, set in an Urban Fantasy metropolis, also features a lot of sewer exploration and adventuring. Archetypal of the human struggle to maintain public health amidst growing crowds and communities, they make great sites for adventure.

Tight, cramped corridors extending into darkness, an ecosystem all its own, you're bound to come across the carcasses of anything and everything the city-above discards. The waste - literal, and metaphorical - intermingle in a sewer. They fit the old-school definition of a "dungeon" or site of adventure even better, I think, than the historical donjons that we got the English dungeon.

To this end, I picked up Beneath the Metropolis | The Secret Lives of Cities by Alex Marshall from my local library.

Friendly reminder to go and support your local library. They have so, so much stuff. And they're free! What a concept...

Beneath the Metropolis has some great comprehensive information on how sewers developed into the broad, expansive networks we think of today from the dead, inert space once occupied only by bones and old cobbles. Undergrounds typically have sewers, but they also comprise all the wastewater tunnels and deliberate infrastructure from generations past.

Cutaways

What drew me initially to the book were these cross-sections of famous cities. Check this out:

Not ashamed to say I stared at this for quite a while.
There's a lot to peruse here: for public utilities to spread out and actually reach the public, pipes have to be laid down. Water has to be kept away from sites of contamination, as well as tunnels for subway cars or smaller pipes for wastewater. A city like San Francisco, back in the 1800s had to deal with a lot of sand dunes and so to this day have compacted layers of sediment that can liquefy and shift the earth around it.

From the cross sections of the 10 cities in the book, here's some lessons that we can draw on for building urban dungeons / adventure-sites:

• Geology has always been a threat to the buildings of a city. Tectonic plates grind together causing earthquakes, sand and silt can liquefy areas the size of whole neighborhoods. Cities that make use of lumber in its construction (or exist in hot, dry places) must constantly contend with fires. 
• Even with magic and supernatural beings, fantasy cities should be threatened by mundane geology. There would be magical geology, too! 
• Imagine what it'd be like to live under a city that's too close to The Underdark...
  
• Big areas and public spaces don't just happen, they're intentional. Communities, guilds or governments drive the public control and operations of a city. Cities are not self-operating organisms but rather evidence of what can happen with intentional, deliberate planning. In the modern day that's state governments, but in fantasy it doesn't have to be.
  
• Underground infrastructure is a reflection of the politics of the past.
  The more fragmented a place is, politically, the harder it is to create large sweeping improvements to an area. 
• For example, Boston has far-less comprehensive subway system than New York (even though they're in the same part of the country and about-as old).
• Cities are like palimpsests. They are continually built and rebuilt over time, continually blurring the line between above and below ground. The bits that aren't fully erased or intentionally forgotten sink down below, turning a city's underground into a kind of collective unconscious.
• For example, take al-Azhar Park in Cairo. Part of the old, Medieval section of Cairo came to be a dump for trash. Almost 1,000 years of trash, until the 1990s when construction began on subterranean aquifers, improving the nearby water-quality and turning the garbage pile into the bed for a new park. Thanks to deliberate, central city-planning,  starting in '04, al-Azhar Park is now a tree-lined promenade with orchards and ponds free to the public.  

Underground as Collective Unconscious

This ties us back from the purely historical back to the fantastical.

I've argued that sewers are great dungeons, and what is a great dungeon but an unconscious expression of its master? This is a sentiment I've seen online in blogs like Permanent Cranial Damage. From the metanarrative perspective of a dungeon being a playground indicative of its designer, what if we zoned in on setting instead? 

The underground of a fantasy world is a chance to highlight its unconscious qualities, to confront the demons and ghosts that it'd rather forget about, to see what is absent shows what the place is really all about. D&D settings like The Forgotten Realms, for example, have The Underdark as their perennial underworld, full of dangerous traps and monsters. This makes sense, in a fantasy pastiche made for a game all about killing monsters!

To create a fantasy city - and its vital underground - is to create a reflection of that city's unconscious. Its history, geology and "Lore" becomes layers, which then can become inspiration for danger, for adventure and for treasure.

To put this thought-process into practice, here's my own attempt at creating a cross-section of my fantasy metropolis Talzur, the City by the Sea.

Talzur is the biggest city in my campaign setting. It's an independent city-state Republic, the crown jewel of its coast, and has a long history with Empires and overseas colonial rule. It defines itself by having destroyed and abolished the trappings of Feudalism, even as imperial control and colonial wealth-extraction are buried far under its foundations.

It's also got 2 million people in it. That's a LOT of people's waste to manage! 

Drawing this out helped me visualize a few things for the purpose of a) creating fun places to explore/delve b) how these layers interact with each other and c) just how Talzur works.

• Sewers are more varied than fantasy settings typically describe. I always think of them like the dungeons in Elder Scrolls: Oblivion, same-y long hallways with a little river running through it. That's a sewer, to be sure, but there are also dry brick tunnels, some wide and some narrow, and all manner of wrong-turns. It'd be impossible to navigate alone in a sewer, and it'd be hard even with a map. Random encounters should likely reflect that. If the object of quests / narratives are in the sewers, players should be able to find them, but it should never be easy.
• The underground should be full of weird, gonzo, even random stuff.
  Empires and kingdoms-long-passed are so far below the surface, nobody should really be "familiar" with them. Places and worlds long-since faded into history have left their artifacts behind, and now exist without their proper place and context. If people went down in the sewers for gold or adventure, they would have no idea what all the tunnels, byways and crevices are, much less the ancient statues, traps and once-magical-infrastructure.
• Even as they are separated in layers, they're all connected. Groundwater seeps between layers and gets in all sorts of places. Even with the presence of large layers of rubble and sand-fills, it could be possible for monsters to assert their territory in large areas of the underground. Everything floats down; from the surface to the upper walkways, down through sand, then flowing into old Marharan drainage that is still, implausibly, in working condition.
• With all this stuff piled on top of itself, there's got to be some magical geology that can change that up.

Magical Geology

So, you've got a city of 2 million people built on some of the world's most ancient ruins. The city is full of everything from high-brow Wizards to Gutterpunk artificers and druids in the parks trying to keep invasive species in-check.

With all that magic concentrated in the underground, and all those spellcasters on the surface, there's got to be some magical feedback and confluence. 

Simurgh Sign: Magical feedback from too many spells cast in an area. This process is more likely in areas with ancient ruins, where magic has already seeped into the foundations. Scholars would call this process Spontaneous Residuum Liquefaction, but most people know it by its effects: a bright red flash like the mythical bird that graces the city's flag: Simurgh Sign. If you see it, you know you should evacuate the area.

Too much magic in an area literally causes the soil to shift. This isn't a hard trigger, its cause is narrative but this can trigger several things:

• Any terrain can be liquified. In real life soil, silt and sand are most likely to become a liquid state during earthquakes, but the magical feedback can liquify even solid materials like stone, marble or concrete.
• Localized "quicksand" like effect when too many spells are cast in an area
• An earthquake like effect from foundations sliding around underneath street-level, effectively replicating an earthquake in a localized area. Street -> The Block -> Neighborhood
• It would take something like a magical atom bomb to liquify a whole district or the city
  
• Sinking and revealing of terrain!
• Something from the surface can disappear from Simurgh Sign, being erased and now only-accessible from the sewers.
• Something from deep down below can settle to the top. This can be something drastic like a dungeon, a treasure vault of trap. This can be something as simple as bits of masonry only of interest to historians, but could even be treasure.

This gameplay is a roundabout way of facilitating why, if the city is built on historical layers, why players / adventurers can still stumble across bits and pieces from anywhere. The city is worn down, sure, but also feedback from so many spellcasters shifts things around if they're not careful. 

And oh, they're not careful, that's for sure!

Terminus

All in all, Beneath the Metropolis was a good book for thinking about building dungeons. Disclaimer, however, that it had a very Orientalist view of cities like Cairo and Beijing. In 2006, no less?
It was hard to parse out useful information with the book talking down to these places as much as just describing them.

Regardless, I hope this inspires you to think about what an underground world says about its surface.

The city begins in the mind, but the mind begins beneath the surface.