This was the very first underground in the world – until then, there were no off-street expressways on the planet. The first 3.6 km line included a station with the famous name – Baker Street. However, this meant nothing to anyone at the time: Arthur Conan Doyle, who would make Holmes reside in this street, was four years old. The tunnels of the world's oldest underground system were shallow trenches covered with a reinforced roof. Passengers had a hard time – the first trains ran on steam power, and the underground was filled with smoke. By the end of the century, the underground was electrified, the escalators were built there, then the familiar diagram was drawn... But the word “metro” was born immediately – London Underground was built by Metropolitan Railway. The word “metro” has been adopted in many cities around the world. But not in London: instead of the letter M, usual for Muskovites, there is a Latin U, because the British call the metro “underground.” However, it is more often called even less officially – the Tube. Those who have seen it say that the name is very accurate.