This is a good joke about a group of American Tourists traveling in England and visiting Runnymede, where the Magna Carta was signed.
A tour bus full of American tourists arrives at Runnymede, near Windsor in England.
They walk up to a large memorial, where they are beckoned to gather around the tour guide who says, “This is the spot where the barons forced King John to sign the Magna Carta.”
A man pushing his way to the front of the crowd asks the tour guide, “When did that happen?”
“1215”, answers the guide.
The man looks at his watch and says, “Shooot! Just missed it by a half hour!”
Image used under a Collective Commons License from https://www.geograph.org.uk/photo/2577154