The Kryptos Sculpture
The Kryptos Sculpture is located in the center of the CIA Headquarters in Langley, VA. It was designed in 1990, and contains a four-part encrypted puzzle. The first three parts have been solved, but now we’ve learned that the second-part solution was wrong and here’s the corrected solution.
The fourth part remains unsolved. Wired wrote:
Sanborn has said that clues to the last section, which has only 97 letters, are contained in previously deciphered parts. Therefore getting those first three sections correct has been crucial.