ACKS Qelong is going well enough we have the highest level PCs at 5th, and we're outgrowing some of the dungeons I originally seeded and hooked.  In ACKS that's moving into overland travel and lair territory, which is cool, but the lair in the last session almost kicked the party's ass, and they're looking to slum it with a dungeon a little bit.  But dungeons for 1st or low level characters are pretty well covered by the OSR, so it's a good time to ask if anyone can recommend any good ones for mid level characters.  Ideally something they can leave and come back to rather than a quest adventure, as the players present can change from week to week.

(And yes, I am going to start rolling up my own, but by the nature of a sandbox I'd like to place more than one.)

Fuck me! My reply got ate!

Many Gates of the Gann.
Several levels of Stonehell
Several levels of The Darkness Beneath from Fight On Magazine
Shattered Skull from Kramer, or maybe Arachnophobia, I think?
Ironwood Gorge says Level 5

White Plume Moutain
A1 Slave Pits of the Undercity

Just a couple that spring to mind.

QuoteRappan Athuk is a diffcult dungeon. Even the upper dungeon levels should not be attempted by a party of less than six characters of 4th
level. Only truly veteran players should attempt this dungeon with lower level characters. Parties delving deeper than the 1st or 2nd levels of the
dungeon should be of 5th level or higher.

It has a lot of material in the 7-12 range and the deepest levels are for 15+ play.

Thanks all!