Westminster Bridge is the green-painted road and footbridge across the River Thames beside the Palace of Westminster, linking Westminster to Lambeth in central London. The current bridge dates to 1862, was designed by Thomas Page, and is known for its seven cast-iron arches and direct views of Big Ben, Parliament, and the London Eye.
It is one of the most recognizable crossings in London because it sits right at the political and ceremonial heart of the city. The bridge is also part of the UNESCO World Heritage setting of the Palace of Westminster and is Grade II* listed
 
Interesting fact...
The bridge’s green color echoes the House of Commons benches, while its Gothic detailing was designed to harmonize with nearby Parliament. It is also one of the best places in London for classic skyline views, especially toward Parliament and the South Bank.