[quote=@Fabulous Knight]
<Snipped quote by poog the pig>
That's a cool idea. I'll go with wells. Holes in the earth that gouge deep into the realm of the occult. Prepare for burrowing centipede-snakes.
[/quote]

Have you heard about how the Nahuatl religions had a Hell/Underworld of sorts that was a real, physical place? It was this spooky cave system that they thought spirits went to in death.

Similarly Mammon could make some of those caverns below the surface into his own little Underworld where mortals might go to do black magic or offer tribute.