There's a sculpture created by Jim Sanborn called "Kryptos" at the grounds of CIA headquarters in Langley, Virginia. Three of the 4 have been solved but the 4th one hasn't been able to be cracked by anyone yet for over 30 years....Click on this Youtube video on the story.
Give it a try and see if you'll be the first to solve this in the world!
Here are the solutions to the previous 3 Kryptos and a hint to the 4th: Click here
There's a Kryptos inspired escape room in Bulgaria called "The Secret of Kryptos". If you have a chance to go there, definitely check it out!
If that's too hard of a chance, give these codes a try (created by cryptanalysts at the FBI Laboratory)
Anyone have the answer?