Subway

Subways, also known as underground railways, were a type of railway infrastructure that existed on Earth in the 21st century. Underground railways included the London Underground tube lines in London, and other railway networks in Barcelona, Washington DC, Santiago, Los Angeles, Beijing, Moscow, Naples, and Paris. (TV: Revenge of the Slitheen)

Subways existed on Earth as late as 2,000,000, when the planet was known as Ravolox. (TV: The Mysterious Planet)