Epic Adventures (3PP or Otherwise)

[Glyfair]

There have also been two epic adventures in Dungeon Magazine: Quicksilver Hourglass (which is ~L30, IIRC), and Eyes of the Lich Queen.

Not Eyes of the Lich Queen, that was the Eberron adventure that WotC published. I don't think it was the one in issue 200 of Dungeon, either where they deal with the Githyanki invasion. That was "only" 18th level.

I think Dungeon only had 2 adventures that were officially epic. A couple of the adventure paths may have had endings that might be epic.