On a sunny June day in Edinburgh, I went to see where my ancestor lost his head. A bagpiper in full regalia played tunes on the Royal Mile, and tourists took selfies beneath the castle, as I surveyed the scene at the Mercat Cross—the site where, on March 26, 1697, Sir Godfrey McCulloch was one of the last people beheaded by the Maiden, a grisly device that forced the doomed to face upwards to watch the falling blade.