The iconic New York City Subway system is the largest rapid transit system in the world when measured by stations in operation, with 469, and by length of routes. New York's subway is notable for nearly the entire system remaining open 24 hours a day, in contrast to the overnight shutdown common to systems in most cities, including Hong Kong, London, Paris, Seoul, and Tokyo. The New York City Subway is also the busiest metropolitan rail transit system in the Western Hemisphere, with 1.75 billion passengers rides in 2014, while Grand Central Terminal, also popularly referred to as "Grand Central Station", is the world's largest railway station by number of train platforms.

Which subway system is considered the largest in the world?