V – Vaults – wealth of city, guilds, nobles, adventurers, etc. Where is it kept? Moneylenders, money changers, bankers, etc. Thieves and Assassins will do a lot to get it. Taxes, etc.

Where is the wealth of the city kept. In a fallen city is any of it still there?

If treasure maps lead to the city, where might it be hidden? Tombs, cisterns, fountains, basements, etc.

Vaults can also hold tombs, coffins, etc. Vaults are also a type of architecture with high ceilings. A vault might have a vaulted ceiling.

For all your cities, living and dead, where is the wealth kept? A high level thief out for a major haul, might want to know. A party more interested in robbing the wealthy than plundering a dungeon might want to know. Nobles, the wealthy, merchants, and anyone with anything that they consider valuable and are concerned others might take it from them, will have some way to protect their stuff. A crazy old man might have all kinds of junk he considers valuable and due to his paranoia devises elaborate means to protect it. This could lead to a lot of people going after what they think is valuable, and it is just junk. Wizards will have protections for their books and scrolls, experiments and items, and more rare spell components. Temples will have divine magics and other things to protect their wealth. Even the poor who have squirreled away a few coppers or silvers will have a hole in the wall, floor, ceiling, or hearth to hide their meager wealth.

A city is a living thing unto itself. The GM will need to have the thieves and others of that ilk doing things, or have a list of things they might be doing, in case players seek it, or something needs to happen in town to keep the game interesting. There could be some famous or rare item that is rumored to be kept somewhere in the city, like a wealthy merchant or noble is known to have the biggest ruby in the land. If the player characters are in town, is it a coincidence that an ambitious thief or gang of thieves have a plan to steal it?

For a fallen city, there will be rumors of great treasures for those who dare to seek it. Where was it kept originally? Is it still there, or is what could not be hauled off hidden nearby, in hopes that those who found it would return?

How might vaults and other stores of wealth be protected?

1. Hidden – Behind a tapestry or curtain, behind a concealed or secret door, under the floor, above the ceiling, by magic either made invisible or disguised. The more unusual and less obvious the hiding place, the better. Hiding in plain sight can be a good one. Location, location, location. It must be difficult for thieves to gain access, but must not be too inconvenient for the owner to get at his or her stuff.
2. Locked – Bars, locks, gates, and anything that presents a physical barrier that prevents just opening the door or lid. This can include magic, like wizard lock.  Where is the key?
3. Guarded – One or more men, monsters, items, spells or a combination thereof can actively prevent access. What is the password? How avoid having to fight the guard(s)?
4. Trapped – Active or passive traps. A pit before a chest is passive. Spring loaded dart traps are active. Again, this can include magical traps, like fire trap. How can one avoid/defeat/circumvent the trap(s)?
5. A combination of two or more of Hidden, Locked, Guarded, or Trapped.
6. A combination of all of the above.

My article for I on Innkeepers touched on hiding places for the proprietor.

Back in February, I wrote a post with some tables on Locks.