This map was inspired by the concept in the reddit post below from Riles42. My thanks goes out to this post: https://www.reddit.com/r/dndmaps/comments/nv90y7/my_take_on_the_city_of_mantolderith_from_out_of/ for the going above and beyond the books concepts.
Below are a list of locations written by Riles42, enjoy the abyss!
1. THE DOCKS - The lifeblood of Mantol-Derith is free trade, so the docks are largely seen as neutral ground for the various gangs, pirates, and merchants the visit the city. Things are kept organized by the Mariners’ Union, one of the most respected institutions in Mantol-Derith.
2. THE GRAND BAZAAR - A vibrant marketplace and a great place for a drunken sailor to burn their hard-earned coin. Casinos, cabarets, exotic foods, and cheaply-made goods can be found here.
3. THE CRACKS - This district is full of culture and crime. Built directly into the walls of the column, this district wraps around the lower section of Mantol-Derith. Fresh air from the Darklake breezes through large cracks in the stone walls, hence the name. Bars, brothels, shops, and homes can all be found here, stacked vertically and accessed by dizzying arrays of lifts, stairways, and ziplines. The various gangs of Mantol-Derith vye for territory constantly, and the streets of the Cracks are the front lines.
4. THE OLDEST HOUSE - The Oldest House district is ancient, as old as Mantol-Derith itself. Its architecture is strange and brutalist, carved out of the rock itself. The layout is erratic and confusing, and what is a cramped corridor one moment may open up into a vast plaza the next. The more open areas have a Roman-esque feel to it. This is where the defacto “government” of Mantol-Derith resides. The Duergar and Drow both have embassies here, and the Council of Thieves meets here every ten tides. It’s also the home base of a mysterious guild of assassins run by the enigmatic mastermind known as “The Mother.”
5. HAG’S END - The poorest of Mantol-Derith’s inhabitants live here in squalor. Overpopulated and underserved, Hag’s End is run by various gangs and is a hotbed for crime and violence.
6. THE GRJUN - Meaning “The Green” in dwarvish, the Grjun is a massive algae farm. It provides fresh water for the citizens of Mantol-Derith, as well as feed for the livestock on small terrace farms located in the city’s smaller outer stalagmites.
7. HIGHCOLUMN - A small, but extremely wealthy district, home of the merchant princes and other powerful players in Mantol-Derith. It gives off strong Bioshock/Zaun vibes. Many artificers and wizards have sought out Mantol-Derith as a place where their studies could continue without the ethics or restriction of government bodies within the Underdark kingdoms. As a result, Highcolumn is a place of excess, terrible secrets, and powerful technology/magic.
8. ZINZERINA’S CROSSING - The largest elevator in the city services all the districts, ending at Zinzerina’s Crossing, a huge transit station providing access to the Grjun and the Spike. Security is high, as residents of Highcolumn are wary of letting any lowfolk into their home district.
9.BRIDGE OF CHAMPIONS - A vibrant walkway into the Spike, decorated with thousands of victorious banners of previous fighters. Contestants fighting in The Spike will remove their banner from the Bridge of Champions each fight, and may only return them after they have won their match.
10. THE SPIKE - The Underdark’s premiere fighting arena, a colosseum carved into a hanging stalactite. People travel from far and wide to fight for the chance to hang their banner in Champion’s Walk. Fights of all kinds take place here. 1v1, 2v2, 5v5, even lesser challenges where brave souls can take on wild beasts from the Underdark. Glory is the ultimate prize, so every contestant is paid a flat rate (any gambling is strictly under the table).
11. OL’ BROM - The skull of an ancient stone giant excavated from the Darklake floor many centuries ago. Ol’ Brom is kind of the patron saint of Mantol-Derith, many fighters will say a prayer for his blessing as they enter the Spike.
