The world's longest circular metro line: Bolshaya Koltsevaya

MOSCOW, RUSSIA - APRIL 19: A woman points a map in subway station at the Moscow Metro, which was opened in 1935 as the first underground system of the Soviet Union and run over the past 88 years, in Moscow, Russia on April 19, 2023. The world's longest circular metro line ''Bolshaya Koltsevaya'', the first part of which was opened in 2018, was put into service on March 1, 2023 with 31 stations at 70 km. The line, which is actively used by 30% of Moscow's population, is within walking distance of 34 district and 1.2 million citizens living in the city center. (Photo by Sefa Karacan/Anadolu Agency via Getty Images)