This list of metro systems includes electrified rapid transit train systems worldwide. In some parts of the world, metro systems are referred to as subways, undergrounds, tubes, mass rapid transit (MRT), metrô or U-Bahn.As of 22 December 2024, 204 cities in 63 countries operate 884 metro lines. The London Underground first opened as an underground railway in 1863 and its first electrified ... More @Wikipedia
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