Today I went to see some wonderful fantasy authors talking about their writing, and Cassandra Clare was one of them. She mentioned a few things that particularly stuck with me: one was that most of us writers are "strange people interested in strange things", and the other was the idea of shadow cities.
Urban exploration is a source of inspiration for Clare. She talked about how she went out looking for the shadow sides of New York and London to research the Mortal Instruments and the Infernal Devices, seeking out the forgotten and mysterious, finding the places where each city’s shadow self lurked most strongly. (Apparently at one point she and Holly Black even got in trouble with the law for sneaking into an abandoned hospital.) She also talked about that game almost every kid plays, where you imagine all sorts of magical things only just outside the corner of your eye, and how, in creating the Shadowhunters and their world inside our real one, she recreated this game, of things that are there that you can’t quite see.
Inspiration for fantasy is all over the place. Even in what we think of as our mundane, everyday world, there are secret places waiting to be discovered. Now, I’m not encouraging you to go break into abandoned buildings, but still. Next time you’re out and about, keep an eye out for the shadow places. There might be spectacular stories lurking inside them.