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

In 1990, artist Jim Sanborn installed a curved copper sculpture named Kryptos inside CIA headquarters. Its 1,735 carved letters contain four distinct secret messages. Cryptographers quickly broke the first three passages, exposing references to Egyptian tombs and agency coordinates. Yet decades later, the final ninety-seven characters remain unsolved. Standard codebreaking fails here because the answer ties directly to physical clues hidden within the surrounding courtyard.