In 2017 I blogged about a Pigpen ciphertext that had been discovered in the London suburb of Croydon. This cryptogram is still unsolved.

The pigpen cipher (also known as Freemason’s cipher) is the most popular secret writing alphabet in history. It has been used to encrypt gravestone inscriptions, treasure maps, certificates, testaments, mug inscriptions, beer labels and more. Today, I’m going to introduce ten especially interesting uses.