Big Ben is the most popular UK landmark

Stonehenge was voted second in the poll, which was launched to mark the birthday of Victorian engineer Isambard Kingdom Brunel.

No Brunel structures appeared in the list of the top 10. This is despite the fact that the poll was launched to mark the birthday of Brunel.

Source: Wikinews

Big Ben has become a symbol of the United Kingdom and London, particularly in the visual media. When a television or film-maker wishes to quickly convey to a non-UK audience a generic location in Britain, a popular way to do so is to show an image of the Clock Tower, often with a Routemaster bus or Hackney carriage in the foreground. This gambit is less often used in the United Kingdom itself, as it would suggest to most British people a specific location in London, which may not be the intention. Big Ben is often polled as the Most Iconic London Film Location.

The sound of the clock chiming has also been used this way in audio media, but as the Westminster Quarters are heard from other clocks and other devices, the unique nature of this particular sound has been considerably diluted. - Reports Wikipedia