A few new pieces secret opening

Alright whipped up a few new pieces and am once again contemplating a dungeon brawl campaign...no really....alright well here are the new pieces.

 ok 3 new floor sections and a door that I dry brushed with green to make it 'corrosive'

A stirway to no where that I could bridge to an adjacent section....the 6" wall to the left is free standing and has a corner on each end...and has a ......

has a removable....'secret door'.  So it can go in front of any 6 inch run...