Nothing says "London" more emphatically than the 318-foot tower housing the giant clock and its resounding bell known as Big Ben. It's as iconic a landmark as Tower Bridge. 

The tolling of Big Ben is known throughout the world as the time signal of BBC radio. Below it, stretching along the Thames, are the Houses of Parliament, seat of Britain's government for many centuries and once the site of the royal Westminster Palace occupied by William the Conqueror.

 Tours of the parliament buildings offer a unique chance to see real-time debates and lively political discussions.