Why is there an U-Bahn sign that goes nowhere? 🚇 🕰️ When this line opened in 1923, it was simply called Nord-Süd, not U6 - it woudn’t be called that until the ‘80s! 🎭 Friedrichstraße sat in the middle of Berlin’s wild Weimar nightlife - bars, theatres and cabarets ✈️ In 1927, the line made history by reaching Tempelhof, the world’s first airport-metro link 👻 The Berlin Wall later turned this stretch into ghost stations beneath East Berlin - the tunnel was used by West Berliners, despite trav