 <translate> This list of metro systems includes electrified rapid transit train systems worldwide. In some cases, metro systems are referred to as subways, U-Bahns or undergrounds. As of October 2014, 157 cities in 55 countries around the world host the approximately 160 metro systems that are listed here. The London Underground first opened as an "underground railway" in 1863 and its first electrified underground line opened in 1890, making it the world's first metro system. The metro system with the longest route length is the Shanghai Metro; the busiest one is the Beijing Subway; and the one with the most stations is the New York City Subway.

Answer this question: when was first metro train started in world? Let's give stream of consciousness first: <yor> Àtòjọ àwọn ètò ọkọ̀ ojú irin alágbèérìn yìí ní àwọn ètò ọkọ̀ ojú irin alágbèérìn alágbèérìn tí ó wà káàkiri àgbáyé. Àwọn ìgbà mìíràn wà tí wọ́n máa ń pe àwọn ètò ọkọ̀ ojú irin metro ní metro, U-Bahns tàbí undergrounds. Ní October 2014, àwọn ìlú 157 ní àwọn orílẹ̀-èdè 55 káàkiri àgbáyé ni ó gba àwọn ètò metro tí ó tó 160 tí a ṣe àkọsílẹ̀ níbí. Ọdún 1863 ni wọ́n kọ́kọ́ ṣí ojú irin abẹ́lẹ̀ nílùú London, ọdún 1890 sì ni wọ́n ṣí ojú irin abẹ́lẹ̀ tí iná mànàmáná wà nínú rẹ̀, èyí ló mú kó jẹ́ ojú irin abẹ́lẹ̀ àkọ́kọ́ lágbàáyé. Ọ̀nà abẹ́lẹ̀ tó gùn jù lọ ni ọ̀nà abẹ́lẹ̀ ti Shanghai; èyí tó gbajúmọ̀ jù lọ ni ọ̀nà abẹ́lẹ̀ ti Beijing; èyí tó sì ní àwọn ibùdókọ̀ jù lọ ni ọ̀nà abẹ́lẹ̀ ti New York City.  Dáhùn ìbéèrè yìí: ìgbà wo ni ọkọ̀ ojú irin metro àkọ́kọ́ bẹ̀rẹ̀ ní ayé? Ẹ jẹ́ ká kọ́kọ́ sọ̀rọ̀ nípa ìmọ̀lára: 