I'm going to be honest, the first time I heard it, I nearly jumped out of my skin. I was somewhere below the Janiculum, doing the very thing I’m about to tell you not to do, chasing monuments, when the whole sky seemed to cough: a boom, flat and enormous, rolling down over the rooftops.
I looked around; nobody else had so much as blinked. An old man on a bench folded his newspaper, glanced at his wrist, and went back to reading. It was noon, of course. Everyone but me had known it was coming.