The Metropolitan District Railway was the predecessor of the District line of the London Underground. Set up on 29 July 1864, at first to complete the "Inner Circle" railway around central London, it was gradually extended into the suburbs. It was a private company that was purchased by the Underground Electric Railways Company of London and moved into public ownership in 1933 as part of the undertakings of the London Passenger Transport Board.
Line openings
The core section of the District commenced at the MetR's South Kensington station and extended in stages to Mansion House. Sections were opened as follows with the District also running westwards over the MetR's tracks to Gloucester Road and High Street Kensington: