The iconic view of a dungeon is of a constructed underground complex stuffed full of monsters and loot. There are other kinds of dungeon, though, ripe for adventure.
Designing a megadungeon is hard. If you don’t get the dungeon’s metaphorical foundations right, you are wasting your time.
Musty dungeon corridors set with uneven flagstones whose walls are daubed in goblin graffiti are infinitely more interesting than “a dungeon corridor.”
Surely designing a dungeon badly is a doddle – just sketch some rooms out and randomly stock them with monsters and treasure? That’s true up to a point, but taking extra time to consider the dungeon’s ecology is design time well spent.
Dungeons that are nothing more than a series of rooms containing a random assortment of monsters and treasures that have no real reason for existing are the result of sloppy, lazy design.
A dungeon needs to be so much more than a hole in the ground stuffed full of monsters and treasures. A dungeon without a purpose is a poor dungeon indeed.
PCs are an inquisitive lot. Irritatingly the more successful ones don’t just charge into the nearest dungeon in search of loot and glory. They ask questions. Lots of questions.
Campaign worlds need deep dungeons, lost dwarven holds, crumbling castles, ebon caverns and dusty necropolises for the PCs to explore. Such locales need suitably evocative names.