D&D 5E An Underdark Market

[Daern]

There's also the Seven Pillared Hall from the 4e module Thunderspire Labrynth that might provide some inspiration. Ruled by a wizard. Minotaur Golem security force. Duergar traders. Halfling tavernkeeper.

 

[Cyan Wisp]

Sounds like those orcs are sitting pretty on the only route to the surface. Maybe an orog among them can figure out how to gouge surface merchants heavily for passage. These gangster orcs would probably get quite wealthy and be able to fortify/staff their position with more and more elite personnel. Under the right management, they might even end up being big players in this part of the Underdark. Orcs in fedoras.