Unsolved
I found a link to an article in Wired about the mystery of the Kryptos sculpture located in the grounds of the CIA headquarters. It’s an interesting read, but it also linked to a page of unsolved codes. The Voynich manuscript, in particular, is fascinating: it made my sci-fi addled mind immediately think of the author as a stranded alien or time-traveller in medieval society…
Mental note: must get out more.