Short answer: I don’t.
Long answer: I research while I’m writing, and sometimes the research inspires the story and sometimes, the story inspires the research. It’s more often the latter, and I sit down with Zoe in a new town, wondering what she would find out there, what would interest her about the place’s complex history, which characters would come to the fore.
The book makes frequent mention of Wikipedia, for good reason! Zoe uses it a lot, and so do I, though of course, it’s not my only source. Local authorities, universities and archeological programmes etc can be great, and books like Watling Street, by John Higgs and The Stone Mason, by Andrew Ziminski, have provided great inspiration along the way.
Zoe doesn’t pretend to be a historian, and neither do I. But, like her, I’ve always wondered about the past, looked at buildings and places and wondered who made their mark there and why. If I wonder enough, I go and find out. I usually wonder enough.
My dream resource for learning about the past is yet to come into being, which is why I’m writing about it, in the hope of somehow triggering that much-needed and wonderful effect. The History Maps.