1869 - East London Line opens (orange line on the map).
1884 - Circle Line opens (yellow line on the map).
1890 - Northern Line opens (black line on the map).
1898 - Waterloo & City Line opens (teal on the map).
1900 - Central Line opens (red line on the map).
1906 - Bakerloo Line opens (brown line on the map). Piccadilly Line opens (dark blue on the map).
1911 - The first escalators are installed, at Earl's Court station.
1913 - First appearance of the circle and horizontal bar symbol.
1929 - The last manually operated doors on tube trains are replaced by air-operated doors.
1969 - Victoria Line opens (light blue on the map).
1979 - Jubilee Line opens (silver line on the map).
November 18, 1987 - A fire at King's Cross station is caused by a burning match falling onto a wooden-tread escalator panel. Thirty-one people die in the fire.
July 7, 2005 - Four suicide bombers detonate themselves
aboard three Tube trains and a bus during morning rush hour, killing 52 people and injuring around 700.
July 21, 2005 -
Four bombing incidents in London take place almost simultaneously, three on subway trains, one on a bus. Three small devices explode at three separate Underground subway stations, two weeks after the July 7 terror attacks. Small blasts occur at Warren Street, Oval and Shepherd's Bush stations. Scotland Yard also responds to an "incident" on a bus at Hackney Road and Columbia Road in east London. There are no casualties.
2007- For the first time, the Tube carries one billion passengers in a year.
2013 - The 150th anniversary.
July 8, 2015 -
A 24-hour strike
begins 6 p.m. local time. The strike action is called after unions and the London Underground fail to agree on a pay deal over a new "Night Tube" service due to start in September.