This sculpture at CIA headquarters holds one of the world's most famous unsolved mysteries

https://amp.cnn.com/cnn/2020/07/25/us/kryptos-secret-message-code-trnd/index.html

(CNN) In the middle of CIA headquarters, there sits a sculpture that contains a secret code that has stumped top cryptologists for decades.

In the late 1980s, artist Jim Sanborn was commissioned to create a sculpture to be displayed at CIA headquarters in Langley, Virginia. Knowing some of the world's top intelligence officials would see the piece practically every day, Sanborn made a work of art that is, in a word, puzzling.

Unveiled on November 3, 1990, it's called Kryptos, and it contains a cryptographic challenge. Surely, someone would crack the code in just a couple of weeks, Sanborn thought.

But no one did. And, today, Kryptos remains one of the world's most famous unsolved mysteries.
"I didn't think it would go on this long -- thirty years -- without being deciphered," Sanborn says.

*snip*