World's 10 Busiest Subways

Moscow Metro, Russia (Ranked 2):

Moscow is the capital of Russia and about 6.6 million people daily ride beneath Moscow and 2.4 billion riders annually. The Moscow Metro was opened in 1935 with one 11-kilometer line and 13 stations. It was the first underground railway system in the Soviet Union. As of 2011, Moscow Metro has 183 Stations, the route length being 305.7 kilometers. The Moscow Metro is opened from about 5 in the morning till 1 AM and ridership is highest during weekdays and lower on weekends. The minimal interval between trains is 90 seconds during the morning and evening rush hours. Since 21^st Century, several projects have been completed, and more are underway. The Moscow Metro Stations are beautifully decorated, representing Russian architecture and art. 

Seoul Metro, South Korea (Ranked 3):

The metro system in Seoul, the capital of South Korea, was opened in 1974, with about 5.6 million riders daily and 2.04 billion riders annually and is third busiest subway in the world. All directional signs in the Seoul Subway are written in English and Korean. Station signs and maps are also displayed both inside the train cars as well as on the subways. The pre-recorded voice announcement in the trains indicates the upcoming station and possible line transfers and all the announcements are in Korean and English and in some cases Japanese and Chinese.