First post!

Okay, obligatory internet memeing out of the way, I want to know what everyone's currently existing megadungeons are? I've worked on a few myself, and they're as challenging as they are interesting. 

My personal favorite is the Caverns of Od Nua, from Pillars of Eternity. The biggest reason is that there was a tight cohesive theme to it. Winding around a colossal, buried statue in search of the spirit of a long dead king.

My other favorite megadungeon is Incandium's Erruption, although as the author of that "mega"dungeon, I'm a bit biased ;)

Let's hear yours, so we can all get inspired by the best of the best.

I've always liked the layout of Stonehell by Michael Curtis. It lays everything out in a useful, GM-friendly format. It's the style I intend use when I make my megadungeon.

Eyes of the Stone Thief qualifies as a different kind of megadungeon, but megadungeon nonetheless. The dungeon is a living entity that eats places and buildings. Some of the things digested become part of the living dungeon making it larger and deadlier. The players are expected to spend a lot of time both inside and outside. When inside, it's about delving another level deeper and when outside it's about going on adventures and learning to hate the living megadungeon which stalks them.

I made a 1-page megadungeon in 2017 that was 5-dimensional and weird enough that the players eventually became more afraid of the rooms that appeared empty than the ones filled with flames or completely full of corpses or horrifying monsters.

I also co-made a dungeon that was a full-sized ruined dwarven metropolis complete with a magical subway system run by a goblin cult, a section overrun by magma elementals, and sewers filled with symbiotic mycelium that produced the city's food in exchange for waste and bodies.

Peach Trees tower block from Dredd?