Next to the Houses of Parliament in Westminster is one of London's most famous landmarks, Big Ben, which is also right next to the Thames.
Big Ben is actually the name of the largest clock inside the clock tower, even though the tower itself is typically called Big Ben. The tower was named after Queen Elizabeth II in 2012 and is known as the Elizabeth Tower.
Big Ben usually chimes hourly but is currently being reconstructed until 2021. The tower is 96m tall and was opened in 1859. In the same area, you can find many other places of interest, for example, the Westminster Abbey church.
The closest underground station to Big Ben is Westminster (Circle, District, Jubilee). Along with the underground, you can conveniently get to Westminster using the Thames Clipper.