Blackfriars station
Blackfriars, also known as London Blackfriars, is a central London railway station and connected London Underground station in the City of London. It provides Thameslink services: local, and regional and limited Southeastern commuter services to South East London and Kent. Its platforms span the River Thames, the only station in London to do so, along the length of Blackfriars Railway Bridge, a short distance downstream from Blackfriars Bridge. There are two station entrances – one on each side of the Thames – along with a connection to the London Underground District and Circle lines.

Blackfriars, also known as London Blackfriars, is a central London railway station and connected London Underground station in the City of London. It provides Thameslink services: local, and regional and limited Southeastern commuter services to South East London and Kent. Its platforms span the River Thames, the only station in London to do so, along the length of Blackfriars Railway Bridge, a short distance downstream from Blackfriars Bridge. There are two station entrances – one on each side of the Thames – along with a connection to the London Underground District and Circle lines.
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