Inaugurated in the 1930s, the mass transit system dates back to the Soviet era. Thus 44 of the Russian capital's metro stations have been declared heritage sites to date. It is estimated that at least 6 million people use the Moscow metro each day. | AP
Delhi's Metro network consists of 286 stations across 390 kilometres. Latest reports suggest that about 5.6 million passengers use the system each day in the post-pandemic era. In 2011, the UN confirmed it to be the first metro system to reduce greenhouse gas emissions in a city. | PTI
The eighth oldest subway system globally, the New York Subway is the world's most extensive with 424 stations. Non-stop service round the clock and seven days a week is another highlight of the NY City Transit. | AP
On June 6 2019, as many as 10.62 million people used the Guangzhou Metro! Covering over 600 kilometres, it operates across 16 lines to date. | Twitter
Often called 'The Tube', it is reportedly the oldest underground transit system in the world. With 272 stations in its fold, it is estimated that at least 5 million passengers use it every day. | AFP
One of East Asia's oldest metro systems, it connects close to 480 stations across 800 kilometres. The world's busiest metro system, the Beijing Subway witnesses an average ridership of well above 10 million! | Shutterstock
Covering 802 kilometres, it is the world's biggest metro system by route length. It is also the world's second-biggest metro system by the number of stations (396). The Shanghai network also clocks an average footfall of well over 10 million commuters, reports say. | Shutterstock