Core Points - The Moscow Metro is celebrating its 90th anniversary, having opened on May 15, 1935, and has become a symbol of the city, representing both its history and innovation [1] - The construction of the metro initially relied on manual digging, but later adopted the use of tunnel boring machines inspired by shipworms, with the first machine purchased from the UK in 1934 [1] - The metro was originally planned to be primarily above ground, but a proposal to build it 35 meters underground was approved by Stalin, despite initial skepticism [1] Group 1 - The Moscow Metro began operations with 13 stations and two lines, expanding to a more complex network over the years, with the first color-coded map introduced in 1957 for foreign visitors [2] - During World War II, the metro continued construction and operation, adding 13 kilometers of tunnels and 7 new stations, serving as both a transportation system and a shelter during air raids [2][5] - The term "Metro" in Russian was originally masculine, but has evolved to be perceived as neuter in modern usage, reflecting changes in societal language [6] Group 2 - The mosaic artwork in the "New Kuznetsk" station was created during the Siege of Leningrad and was installed to honor the artist's efforts despite the dire conditions he faced [3] - The Moscow Metro features two stations named "Arbat" and "Smolensk," a result of wartime air raids that led to the construction of duplicate stations [4] - The metro system is one of the longest and most extensive in the world, with a 60% increase in stations from 2010 to the present, now totaling 302 stations, and has implemented modern technologies for passenger convenience [10]