The Beale Ciphers are a set of three ciphertexts that supposedly reveal the location of one of the grandest buried treasures in U.S. history: thousands of pounds of gold, silver and jewels. The treasure was originally obtained by a mysterious man named Thomas Jefferson Beale in 1818 while prospecting in Colorado.
Of the three ciphertexts, only the second one has been cracked. Interestingly, the U.S. Declaration of Independence turned out to be the key — a curious fact given that Beale shares his name with the author of the Declaration of Independence.
The cracked text does reveal the county where the treasure was buried: Bedford County, Virginia, but its exact location is likely encrypted in one of the other uncracked ciphers. To this day, treasure hunters scour the Bedford County hillsides digging (often illegally) for the loot.