This mysterious CIA sculpture has stumped code breakers for 30 years

A modern-day treasure hunt on the grounds of CIA headquarters in Langley, Virginia, has been a challenge to cryptographers for 30 years. The fourth and final piece of the puzzle remains unsolved to this day.

The 12-foot sculpture, called Kryptos, stands on the grounds of the famous CIA complex in Langley, Virginia and was created by the American artist Jim Sanborn, 25 years ago.

Kryptos contains four hidden messages, carved out of metal. The four messages are the clues to a riddle. The artist has previously suggested that solving the final riddle will be akin to a treasure hunt on the grounds of the intelligence agency's headquarters.

Three of the messages hidden in the sculpture have already been solved. The fourth, however, has not. The message is 97 letters but no one has been able to decipher it so far.

Even the code-cracking mega minds at America's ultra secret National Security Agency, who were the first ones to solve the other three parts, have given up.