The famous Mind the Gap sign in the London Underground

Dynamic image of the London Underground with a Tube train speeding along the curved platform of the station. The famous yellow "Mind the Gap" sign on the platform edge warns passengers of the space between the train and the platform, becoming over time one of London's most recognizable symbols. The red, white and blue carriages of the Tube, as Londoners affectionately call their metro, speed through the tunnel while commuters wait seated on benches. The London Underground, opened in 1863, is the oldest in the world.

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