The London Underground logo is the most famous and most success roundel logo so far.
The current London Underground logo was designed by Edward Johnston according to Frank Pick’s idea in 1915, and registered the symbol as a trademark in 1917.
But the London Underground logo was inspired from a roundel symbol appeared in 1908, when the UERL placed the station name above a solid red round.
As of 2013, forms of the roundel, with differing colours for the ring and bar, is used for other Transport for London services, such as London Buses, Tramlink, London Overground, London River Services and Docklands Light Railway.
The London Underground is a public rapid transit system opened in 1863, is the world’s first underground railway, is now a wholly owned subsidiary of Transport for London (TfL).