Cannon Street station
Cannon Street station, also known as London Cannon Street, is a central London railway terminus and connected London Underground station in London fare zone 1 located on Cannon Street in the City of London and managed by Network Rail. It is one of two London termini of the South Eastern Main Line, the other being Charing Cross, while the London Underground station is on the Circle and District lines, between Mansion House and Monument stations. The station runs services by Southeastern, mostly catering for commuters in southeast London and Kent, with occasional services further into the latter

Cannon Street station, also known as London Cannon Street, is a central London railway terminus and connected London Underground station in London fare zone 1 located on Cannon Street in the City of London and managed by Network Rail. It is one of two London termini of the South Eastern Main Line, the other being Charing Cross, while the London Underground station is on the Circle and District lines, between Mansion House and Monument stations. The station runs services by Southeastern, mostly catering for commuters in southeast London and Kent, with occasional services further into the latter
Check the official site before travelling; hours and prices can change.
More bridges

Tower Bridge
The bridge people mean when they say London Bridge. Walk the high-level walkway for the glass floor.

Millennium Bridge
Foot-only suspension bridge from St Paul's to Tate Modern — the only crossing aligned on St Paul's dome.

Hammersmith Bridge
Currently pedestrian-only, Victorian wrought-iron beauty — best photographed at golden hour.
Source: wiki-list