Where the facts come from
Every factual claim on this site links to its source. This is the full list.
How we checked
Each fact was written in our own words alongside its source. Our build script stores the text of every source and, for each fact, checks that the key words and figures really appear in it. 120 of 120 checks passed when this site was last built (10 November 2026). Where we couldn’t find a named source saying something, we left it out. Where good sources disagree, we say so and give both.
Where sources differ
- Length of the first line. 5.6km (London Transport Museum, Metropolitan line page), three miles (London Transport Museum, Victorian transport page), or 3.75 miles (6km) authorised by Parliament (Britannica).
- Stations on the first line. Seven stations, both ends included (London Transport Museum), or six intermediate stations (Transport for London).
- Size today. 11 lines, 402km and 272 stations (London Transport Museum; TfL gives 272 stations and 11 lines), or about 400km and some 270 stations at the start of the 21st century (Britannica).
All sources (12)
- Transport for London: London’s transport, a history: London Underground (27 facts)
- London Transport Museum: Public transport in Victorian London: Underground (15 facts)
- Britannica: London Underground (with Britannica’s subway article, on the same page) (10 facts)
- London Transport Museum: Transforming the Tube map: Harry Beck’s iconic design (10 facts)
- London Transport Museum: A very short history of the Underground (9 facts)
- London Transport Museum: Mapping London: the iconic Tube map (9 facts)
- London Transport Museum: Deep-level shelters (8 facts)
- London Transport Museum: Metropolitan line (8 facts)
- London Transport Museum: The evolution of the roundel (8 facts)
- London Transport Museum: Edward Johnston, the man behind London’s lettering (7 facts)
- London Transport Museum: The world’s first underground (5 facts)
- London Transport Museum: Shelter in wartime (4 facts)