Speaking of dungeons being used as a campaign setting, there's a number of anime and JRPGs that use a massive tower as a dungeon substitute.

The Tower of Druaga has a town that's built up around the base of this massive dungeon like tower and the economy is mostly based off the loot that adventurers bring out of the tower. There's also a military outpost with an attached settlement halfway up the tower as a safe refuge for tower climbers.

Azure Dreams is an old PS1 game with a similar setup, except that the adventurers capture and train monsters from the tower ala Pokemon.
The rest of the game is essentially a roguelike with dating sim and town improvement elements (it is a Japanese game with all the oddity that involves ).