Unlike the American Revolution, the French version is best forgotten, especially to those on the short end of it - and it wasn't just the current monarchy that got punished by the philosophy of the day.   In 1793, revolutionaries also desecrated the tombs of previous monarchs, including  assassinated King Henry IV - it had been a hard time to be a Protestant king in France in 1610, it seems, so Henry was murdered, and then 180 years later the French stuck it to him again.   After executing Louis XVI, the current monarch, they went after the old ones.

Like Louis, Henry lost his head during the Revolution, though not to a guillotine.    But it went into circulation and it was reputed to be in the hands of private collectors since - including the brain.  All of it remarkably well preserved.   

Researchers recently compared digital reconstructions made using the head with sculptures and portraits of Henry...and found they matched.   Radiocarbon dating also matched the king's date of death.  Though no un-contaminated DNA could be found, that is a pretty good indication the head actually did belong to the murdered and later desecrated king.   Various facial features in art matched the head.

Mummified Head Identified As King Henry IV of France

Livescience writer Stephanie Pappas has the full story.