Favorite Dungeon Type/Location
Ruins. I like ruins. I like things crashing down and falling apart. I like the threat of fixtures breaking when you touch them. I like hallways that end in walls of rubble, and adventurers squeezing through fault cracks that have opened up new routes taking them to places they were never meant to go. I like the floor covered in a layer of scree so thick that every time the fighter rolls a Stealth check, it sounds like he’s running a rock polisher.
I like crumbling keeps and decaying castles whose original function is long gone, and which have been repurposed a hundred different times by fifty different armies and fifty different groups of monsters before the PCs ever set foot on the threshold. I like a dungeon that has its own dungeons, which in turn have their own dungeons, which neither of the groups who built the first two levels of dungeons had any knowledge of.
I like ruins because I like history. I like the idea that each generation of exploration and imperialism in a campaign world is forced to walk over and across the bones of the kingdoms and empires that rose and fell before it. I like the idea that adventurers can touch this history — and that this history can often touch them right back, in ways that aren’t always pleasant.