In this prologue to the Hit and Run History | WGBH web series, the crew tracks down the oldest and rarest of all American coins: The Columbia and Washington Medal. It was minted in Boston in 1787 to commemorate the first American voyage around the world. Today, less than 20 survive. Hit and Run History goes to the Massachusetts Historical Society to see three of them. The names of the men inscribed on the back are some of the subjects of this series.