The first section, from Walthamstow Central to Highbury & Islington, opened in September 1968 and an extension to Warren Street followed in December.

The line serves 16 stations and all but Pimlico provide interchanges with other Transport for London or National Rail services.

With trains arriving every 100 seconds at peak times, it is one of the most frequent rapid transit lines in the world.

[2] In 1948, a working party set up by the British Transport Commission (BTC) proposed a tube railway from Victoria to Walthamstow,[3] largely based on a 1946 plan for a Croydon-to-Finsbury Park line.

[4] Other benefits were linking the key railway stations at Victoria, Euston, King's Cross and St Pancras and improving connections between north-east London and the city.

[7] A private bill was introduced in Parliament in 1955, describing a line from Victoria to Walthamstow (Wood Street), next to the British Rail station.

Another proposal, not in the bill, supported an extension from Victoria to Fulham Broadway on the District line terminating at Edmonton instead of Walthamstow.

[9] During the planning stages, it was known as Route C and named the Victoria line (after the station) by David McKenna, Chairman of British Transport Advertising, whose suggestion was seconded by Sir John Elliot.

[9] Initial construction began in January 1960, when two test tunnels were started from Tottenham to Manor House under Seven Sisters Road.

The tunnels were excavated using an experimental "drum digger" rotary shield, powered by hydraulic rams, that could cut more than 60 feet (18 m) per day.

[17] After the line gained parliamentary approval on 20 August 1962 with a budget of £56 million, construction began the following month.

[18] The economic boom of the mid-to-late 1950s had faded leading to a rise in unemployment in London, and the government had hoped that building the Victoria line would alleviate this.

[20] A steel umbrella was erected over the junction in August 1963 so that a new ticket hall could be built without disrupting existing traffic.

[39] The Kentish Town to Barking line did not close as expected and both stations at Blackhorse Road remained open.

The London Police wrongly detained and fatally shot 27-year-old Jean Charles de Menezes once he boarded a train at one of the stations on the Victoria line.

[45] Services resumed the following day after sugar was used to slow the setting of the concrete and make it easier to shovel out.

[56] In late 2010 and 2011, platform humps were installed on all Victoria line stations except Pimlico to provide step-free access to trains.

[61] It is the sixth-most heavily used line on the network in absolute figures, but in terms of the average number of journeys per mile it is by far the most intensively used.

[64] During off-peak periods, the Victoria line runs 27 trains per hour between Brixton and Walthamstow Central.

[79] In combination with new, faster trains, the line's capacity increased by 21%, equivalent to an extra 10,000 passengers per hour.

[19] Examples include narrower than usual platforms and undecorated ceilings at Walthamstow Central, Blackhorse Road and Tottenham Hale, affecting lighting levels.

Special "local arrangements" are in place should it be necessary to evacuate passengers from trains via Netherton Road emergency escape shaft.

[93] Planning permission for a shaft at Ferry Lane, next to Tottenham Hale station, was granted on 11 January 1968, during the first phase of construction.

[94] By mid-2009, trial boreholes for a cooling system at Green Park station had been drilled and more were scheduled to be created by the end of 2009.

[97] By 2009, changes at Cobourg Street were in the planning stage and demolition at Moreton Terrace, Somerleyton Road and Drayton Park shafts had taken place.

[99][100] The depot at Northumberland Park, the service and storage area for trains, is the only part of the Victoria line above ground.

It is next to Northumberland Park railway station, on Tottenham Marshes in the London Borough of Haringey, over a mile from the Victoria line.

[104][105] It was announced by Haringey Council in its 2012 A Plan for Tottenham report that there was "potential for a Victoria Line extension to Northumberland Park".

Herne Hill would be on a large reversing loop with a single platform removing a critical capacity restriction eliminating the need for trains to reverse at Brixton and provide a more obvious route for passengers who look for the nearest tube station before any other transport options.