Back when I lived in Hamburg, I had a WWII above-ground air raid shelter (“Hochbunker”) for a neighbour.
Cleverly painted to match the row of houses it was part of, it was a rectangular, windowless structure, roughly 5 stories high, with 6 feet thick concrete walls. The interior took the form of a helix-like tunnel, a bit like a parking structure. At the time, it was being put to use as a furniture warehouse, and attempts had been made to carpet and panel, but you could still see the attachments for the bench seats that would’ve lined the walls, and the ventilation system was pretty much like the original. Imagining people huddled up in there as the building shook wasn’t hard at all. (Incidentally, thousands of people perished in structures just like it. You can build to withstand bombs, but firestorms are another matter. The bombing of Hamburg was aptly codenamed “Operation Gomorra”.)
The city didn’t exactly like having dozens of these reminders of very bad times around, but demolishing them turned out to be completely impractical - a few attempts only had the effect of turning a concrete eyesore into a structurally unsound and dangerous eyesore. So people paint them over, try to find uses for them, and otherwise turn a blind eye.