If we're expanding this thread to talk about doors as well, then the Foundry Town Hall took me some hours and several levels to locate. I went through all the shops, did as much of Evelyn as I could without dobbing her in to a cop (couldn't find any that would talk about it), looked through all the mines, zapped Nicolas, etc., broke into every house, argued with the Mysterious Man. Eventually, only with the aid of the wiki saying there even was a town hall with a chief I needed to find, and with the aid of the map screenshots on the wiki I realised that what looked like a grey "the end of the map" wall at the NW corner of the SW map actually had a grey door in it behind a foreground tower made of corrugated iron and girders. This lead to a narrow room (actually on the edge of the map) where all the action was. A bullet-proof glass panel, or an open door, or a bubble help when Tab is held would have helped a lot.
Similarly, Estelle's pharmacy has a nigh invisible door in the SW corner that blends in with the corrugated iron panelling around it and it's on a surface hidden by a corner of the building. I had no idea it was there and only traded with her through the wall, by entering the building through the forbidden door in the NE corner. At the top of the slums stairs there's a house with two pairs of boots beneath the "broken pixel" artwork and this house has an obscured door too. Not getting into Pointless House doesn't matter. Not getting into Estelle's pharmacy except via a forbidden door watched by a sniper is more confusing. Not getting into the hidden Town Hall is a quest blocker for numerous quests.
Maybe all transition zones (red), teleport zones (blue) and doors should have bubble help that appears when you hold Tab? Stairs Up already do, so why not transition zones too? Trapdoors already do, so why not real doors too?