D&D 5E What are your favorite megadungeons (that could be easily adapted to 5E)?

[Mercurius]

I'm in the process of designing and populating a sandboxy region for my 5E campaign to start in January, and wanted to throw a megadungeon or two into the mix - that would be easy(ish) to run and adapt to 5E, has a sense of variety and deadliness, and a feeling of endlessness (in other words, I like the thought of the PCs randomly coming across it and discovering that it goes on for...ever...seemingly, at least!).

A couple that I own: the old Ruins of Undermountain box set and the Castle Whiterock box set. I also ordered the Emerald Spire for Pathfinder. I'm aware of numerous others: World's Largest Dungeon, Vault of Larin Karr, Rappan Athuk, Dwimmermount, Castle Greyhawk, Slumbering Tsar, Lost City of Barakus, Doomvault, etc....anything that *you* like in particular, with an eye for adaptability to 5E? In particular I want megadungeons that are (relatively) easy to enter and leave, so that the PCs can go at them for awhile and even if they leave, they know they are there and can always return to them.

 

[meomwt]

Larin Karr isn't so much a mega-dungeon (though it could be treated as such), as a campaign sandbox where adventuring sites can be linked by Underdark passages. There is a plot, but no driving motivation to find the treasures (unless you, as DM, add one).

Barakus is a great idea and should be relatively easy to convert. There is a large dungeon (5 levels), plus overland travel, city adventures, etc. The city is a good base for low-level characters, though any city could substitute with some work. I added some city adventures and political wrangling when I ran it (years ago), though we didn't get far into the dungeon itself. The adventure is good as a "starter" at first level.

Also from Necromancer Games is Tomb of Abysthor - haven't run it but have read through it. Several big levels and a few small ones, factions fighting for control and a search to cleanse the Tomb of evil. Might be harder to convert than the others (at least, until the DMG arrives and villain options become more apparent), but it is a significant challenge.

 

[Tharian]

I haven't done much work on it yet, aside from re-reading a lot of the first book in the box set to get familiar with the story line once more, but I'm looking at updating Night Below.

We've had one session so far and the second is set for next Saturday so we'll see how things go.