An RPG Resource Review:
While many of 0one's Blueprints are single locations, this one is a complete - if compact - dungeon! There's a short backstory which explains the dungeon's name and gives you some idea of how to populate it, but of course you can substitute any appropriate story more suitable to events and locations in your campaign.
The dungeon consists of a ground level, a small cave system that serves as the entrance, and three levels of underground complex. The ground level is very overgrown and has but the remains of a small guard post still more or less standing. If you're lucky (or is that unlucky) you can find a path to a bone-strewn cave entrance which leads to the horrors beyond!
The initial caves lead to constructed areas which are under a long-gone castle, and both the cave system and the built bit lead down to 3 lower levels. It's quite a big complex actually, although in a state of disrepair with a lot of cave-ins and fallen rocks... and may well prove to still be unstable when your adventurers start rooting around.
The usual technical talents of 0one allow for customisation to some extent - print blue or black and white pages, have a compass rose or grid overlay and so on.
This is a fine example of what might be left behind when the above-ground structures are long gone, and provides plenty of scope for a traditional dungeon-crawl.
Ĝone's Blueprints: The Ruined Town, Dungeon of the 13 Undead