In 1990, Jim Sanborn installed Kryptos with 4 encrypted sections at CIA headquarters. 36 years later, its final section remains unsolved despite decades of codebreaking

A sculpture at CIA headquarters has spent 36 years doing something unusual: asking people to solve a message that was deliberately built to resist them. Installed in 1990, Kryptos combines copper, stone, water and petrified wood with four encrypted sections of text. Three have been deciphered, but the final section remains unsolved, keeping one of Washington’s most unusual public artworks tied to the history of modern codebreaking.

The work was created by James Sanborn, a Washington, DC native whose sculpture was designed specifically for the Central Intelligence Agency campus. Rather than hiding the encrypted material inside a document or computer system, Sanborn placed it in plain sight on a large copperplate screen between the CIA’s Original Headquarters Building and New Headquarters Building. Letters cut into the metal form the visual and cryptographic center of the installation.