Well, there was those group of people near my town that explored a network of sewers and found them so similar to the Submachine ambiances, there was a paragraph on the Wikipedia article. At this point I don't even know if it's true or not, because it's been removed.
This is the sort of stuff that would have inspired submachine. Mateusz said that nothing specific inspired submachine, so the inspirations are all over the place. Red-brick architecture – I think we can safely assume – being one of these many inspirations. Remember the secret in sub4 with the shipyard? I assume that's the specific inspiration of that architecture in submachine. What we are seeing here are images of similar architecture (or formations replicating similar architecture).
Balance is imperative; without it, total collapse and destruction is imminent.