On any given weekday, nearly 9 million people ride the metro from the outer edges of the Russian capital into downtown Moscow, making it the second most heavily used metro system in the world after Tokyo's subway.
The average length of a trip on the Moscow metro is 13 kilometers.
But before passengers can ride, they must first get through the huge crowds massing at the ticket turnstiles, on the steep, quick escalators and on crowded platforms.so
The longest escalator in the Moscow metro system is 126 meters.
The subway boasts 172 stations in all, 71 of them deep underground.
During the Cold War, some stations were planned as shelters in the event of nuclear attack.
Opened in 1935, many Moscow metro stations stand out for the ornate socialist realist art featured on the station walls and ornate chandeliers illuminating the long, cavernous tunnels.
Most stations feature long platforms that can accommodate up to eight rail cars, with trains running roughly every 90 seconds.
The Moscow metro is nearly identical to those used in all other former Soviet and Warsaw Pact cities where there is a metro, including St. Petersburg, Minsk, Kyiv, Sofia, and Warsaw.
Moscow metro officials say more than 36,000 people work to run and maintain the subway, the most reliable form of transport in the traffic-clogged city.
In recent years, several reconstruction projects have been completed and more are underway. Officials are also planning several extensions of existing lines as the Russian capital continues to grow.
Some information for this report was provided by AP, AFP and Reuters.