On St. Patrick’s Day, some 35 Yale alumni and family members gathered just off the Baltimore-Washington Parkway to tour the National Cryptologic Museum, the National Security Agency’s (NSA) tribute to code-breaking and signals intelligence. We learned about the interception and decoding of Germany’s Zimmerman Telegram, which sought to bring Mexico into World War One against the United States; World War II’s famous German Enigma cipher machine and the three young Polish cryptanalysts who deciphered it; how the U.S. military broke the Japanese naval codes and used the resulting knowledge to win the critical battle of Midway; and the role that eavesdropping and high-level surveillance played during the Cold War. We saw a working Enigma code machine from World War II, a microphone the Soviets secretly installed in a wooden Great Seal in the U.S. mission at the U.N., and a fragment of the U-2 spy plane flown by Francis Gary Powers that was shot down in 1960 (part of the background to the movie Bridge of Spies). A huge thanks to the National Cryptologic Museum for the warm welcome and for sharing their knowledge!