Richness of history. As other comments say, it's a versatile slice of an ex-industrial heartland. Some bits are Tudor (Shakespeare lived up the road in Stratford), Then it was a powerhouse right through the industrial revolution, well connected by canals and rail (technically Birmingham would make a great New Green Capital when the sea reclaims London). Then Hitler dropped several Hiroshima's worth of bombs on Britain in a WW2 campaign we called "The Blitz". A lot of that fell on Coventry and Birmingham causing millions of pounds of improvements :) So it became a testing ground for new and innovative architecture, some of which was the Brutalist concrete of the late 50s and 60s. That looked great and "modern" at the time, and now looks a perfect "dystopian" setting. Last time I visited that was being bulldozed, but preservation orders actually protect some of the "ugliest" skyline, because that's part of our culture now. So, if you're looking to make a dark post-industrial apocalypse move, come check out Birmingham.