Helvane's Tower is a bit different, as it was not designed to be a dungeon. I ran a character who was a dimension lost Sindar Elf. He eventually ended up in Tim Anderson's campaign in Redding, CA. I was living in San Jose at the time, so only played every several months of so. After a very rich haul I managed to hunt down a suitable tower to buy and establish myself as a research wizard. Tim gave me free reign to design the upper levels, then we gamed out exploring the under levels on several of my visits.
Landscape view. The barns off to the left are the experimental distillery where I crafted fruit ciders and brandies. Helvane specialized in potables and alchemical transformations.
Of more interest are the detailed floors of the tower. I have another version with numbered areas somewhere to find. The tower was used as dungeon a few years back for some lower level players. Quite a bit of fun.
And the cellar level...
Note the passage guarded by the deadfall door. It leads down miles, to the Underdark...