There's a Victorian chapel in one of the hospitals at GOSH, designed by the same guy who did Westminster.
Marvel of engineering, but built around miasma theory (need lots of light and aerated sections to keep bad air at bay) which fell out favour when germ theory came into being (sterilise everything, and you're fine), so the big spaces became impractical.
By then the chapel was Grade II listed, so they couldn't knock it down. So they smashed everything around it, underfitted it and moved it down, and then rebuilt the hospital around it.