St Magnus the Martyr, London Bridge, is a Church of England church and parish within the City of London. The church, which is located in Lower Thames Street near The Monument to the Great Fire of London, is part of the Diocese of London and under the pastoral care of the Bishop of Fulham. It is a Grade I listed building. The rector uses the title "Cardinal Rector" and, since the abolition of the College of Minor Canons of St Paul's Cathedral in 2016, is the only cleric in the Church of England to use the title cardinal.

London Bridge refers to several historic crossings that have spanned the River Thames between the City of London and Southwark, in central London since Roman times. The current crossing, which opened to traffic in 1973, is a box girder bridge built from concrete and steel. It replaced a 19th-century stone-arched bridge, which in turn superseded a 600-year-old stone-built medieval structure. In addition to the roadway, for much of its history, the broad medieval bridge supported an extensive built up area of homes and businesses part of the City's Bridge ward and its southern end in Southwark was guarded by a large stone City gateway. The medieval bridge was preceded by a succession of timber bridges, the first of which was built by the Roman founders of London (Londinium) around 50 AD.