Things are connected in ways that we don't always see at first. A couple weeks ago I was listening to an iTunes U lecture about the Roman Empire and the Emperor Hadrian. He was a hands-on kind of emperor, traveling around getting things done.
This week I listened to The Zombie Survival Guide, and it turns out that Hadrian's Wall was built to "isolate Northern Caledonia from the rest of the island." after a Class III zombie outbreak.