 The station is in two parts : sub @-@ surface platforms opened in 1870 by the District Railway ( DR ) as part of the company 's extension of the Inner Circle eastwards from Westminster to Blackfriars and deep @-@ level platforms opened in 1906 by the Baker Street and Waterloo Railway ( BS & WR ) and 1914 by the Charing Cross , Euston and Hampstead Railway ( CCE & HR ) . A variety of underground and main line services have operated over the sub @-@ surface tracks and the CCE & HR part of the station was reconstructed in the 1920s . 
