What are numbers stations? What does music have in common with spying? How does the famous Enigma machine work? How has encryption affected the course of history? The exhibition at the Museum of Municipal Engineering reveals the secrets of past and present cryptography. We will see antique telegraphic, telephonic and radio equipment once used by the military, secret service and underground opposition in Poland and test our spying skills by trying to pinpoint an enemy’s radio station or break encryption codes. We will also learn more about contemporary coding in the political and military worlds as well as our everyday lives.