When creating dungeons, I like to try to give them a history beyond "old place with traps and monsters and gold", since I like everything to feel real and have a purpose. However, whenever I try to map out one of these, they either end up with planning that doesn't make sense for what it is, or wouldn't be fun to play through.
How do I create a dungeon layout that has/had purpose and would still be fun and challenging to explore?
If you're really interested in verisimilitude, you can look at floor plans from the internet. For example, if I wanted to make a manor, I could do a bit of googling and find a floor plan like this, which looks like it could make for a decent house-based dungeon crawl:
Alternatively, if you wanted to have some ancient temple or tomb, you could look for similar things in the real world. The Great Pyramid near Giza, Egypt has a layout somewhat like this:
When I plan dungeons, I sometimes try to make sensible dungeons, where each room has a purpose. But honestly, I don't feel like many people really care about that: I've never heard someone ask, "but what is the original purpose of this room?" Because you're ultimately planning for a game that is fun, "making sense" kind of falls by the wayside.
Depending on the kind of game you're playing, you have access to lots of things the real world doesn't. I've run a sprawling, multiroom dungeon with infinite floors before. None of the rooms make any sense from a usability or architectural standpoint, but my excuse was "a mad god did it". If you think a certain structure can be fun to play, you can just insert it and come up with a justification later.
Finally, if you want a real-world example of dungeon-like buildings that are full of real purpose and history but make no sense, look to the Winchester House in California. From Wikipedia:
Since its construction in 1884, the property and mansion were claimed by many to be haunted by the ghosts of those killed with Winchester rifles. Under Winchester's day-to-day guidance, its "from-the-ground-up" construction proceeded around the clock, by some accounts, without interruption, until her death on September 5, 1922, at which time work immediately ceased.
It looks something like this:
Doesn't that sound like a great place to run a dungeon?
This game may be the solution you're looking for. It is a solo game for building a dungeon that is supposed to present logical events occurring in the dungeon throughout different epochs of time through rolling on random tables. I've only purchased the game; I haven't played it, so I can't confirm that it results in a logical layout. This may depend on your intuitive grasp of interior space.
But, from a read through, it's not going to be one of those games where you roll a table to literally randomly generate each and every corridor. Each Age adds a new strata of the dungeon, that you build/draw as you play. The game may help you to consider the logic and history behind how your dungeon is laid out.
