@ChurchWindows
"Lobbies between two doors. One closes behind you then you're in some kind of air lock space before you can reach the next one. Often in art galleries."
You'd have loved the old Mersey Rail train of my youth. The trains would consist of either one set of three interlocking carriages, the end one of which contained the driver compartment, or two of these sets to form six carriages altogether.
Anyway, If you wanted to move from one carriage to another, you had to open the sliding door, then step into this small space with what looked like a sort of grubby off-white, rubbery concertina "floor" beneath your feet, which covered the links between the carriages, and which was wobbling about if the train were in motion, before quickly sliding the door behind you shut, and sliding open the door in front of you to enter the next carriage. All the while shaking from side to side as the train moved.
Some people wouldn't bother to shut the door behind them, so some pissed off traveller in the nearest seat would have to get up and shut it.
More recent stock allows people to see and walk unhindered all the way through the entire train, on solid flooring. But we were made of sterner stuff back then. 😅