The CIA is home to many secrets, but perhaps none so tempting as those punched into a sculpture that sits in its courtyard. Erected in 1990, "Kryptos" features four undulating panels of copper that contain four secret puzzles, three of which were solved in 1999. But the fourth continues to stump would-be code breakers, much to the surprise of Jim Sanborn, the sculptor who created it. "I assumed the code would be cracked in a fairly short time," he says—and so he's finally offering a clue. Sanborn gave the New York Times the answers to the 64th to 69th letters in the passage.
They read NYPVTT; deciphered, it's BERLIN. But 91 characters remain. The two left-hand panels contain the messages; the right-hand ones provide the key to cracking some of it. Each puzzle is encrypted differently—and some contain misspellings, to make it even trickier. But Sanborn is tired of dealing with the calls, emails, 100-page-long papers, and visits to his home from code breakers explaining their "solutions" to the 97-character puzzle—he claims no one has gotten more than two letters right. Hence, the clues. "I can’t do this for many more decades, OK?” Sanborn says. “I’m 65 now. They might get some more clues at 75. But 85?" Click here to read what the three cracked puzzles say.