An unsolved mystery has hidden in plain sight at the headquarters of the Central Intelligence Agency (CIA) in Langley, Virginia. It has nothing to do with covert spies, double agents or state secrets.

When artist Jim Sanborn talks about “Kryptos,” his sculpture at the CIA headquarters, and the famously unsolved secret code engraved in its copper panels, he sounds as if he’s talking about espionage, ...

This undated photo provided by the Central Intelligence Agency shows the 1990 dedicated sculpture "Kryptos" by James Sanborn at the Central Intelligence Agency in ...

It is one of the world's most famous unsolved codes whose answer could sell for a fortune -- but two US friends say they have already found the secret hidden by "Kryptos." ...