Big Ben
Big Ben is part of the Houses of Parliament building, where there has been a parliament since 1275. However, Big Ben is not the name of the Clock Tower, but rather the name of the bell inside! The Houses of Parliament is home to the House of Commons and the House of Lords. It has 1100 rooms and one of the most spectacular medieval timber roofs in the world. Some sessions are open to the public to watch from the Visitor's Gallery (Mon-Wed 2:30-end, Thurs 11:30 on) to which entrance is free.
Buckingham Palce
Built in 1705, Buckingham Palace became the London home of the sovereign in 1837, with Queen Victoria. You can tell if Her Majesty is at home because the royal standard replaces the Union Flag when she is in residence. The State Rooms of Buckingham Palace are open to the public during August and September and Changing of the Guards takes place daily. The Royal Mews, home to the collection of royal state carriages, can be accessed through an entrance to the left of the palace.
Tower of London
For over 900 years the Tower of London has dominated the city of London. It has been a Royal Palace, Prison, Place of Execution, Fortress, Arsenal, Royal Mint and Jewel House. The Tower of London is home to the Crown Jewels, this includes the Imperial State Crown worn by the Queen at the opening of Parliament. You can also see one of the largest diamonds in the world at the Tower of London, the Cullinan 1, set in the Sovereign's Sceptre, which is kept in the Jewel House dating from 1660.
Tower Bridge
Tower Bridge was completed in 1894 and has become one of London's most famous landmarks. It was the last road bridge built in London that is able to open in order to let tall ships through. Two massive Mock-medieval towers bear the weight of the bascules which raise the central section to allow ships to pass. Inside the bridge The Tower Bridge Experience attraction takes you on a tour that shows you how the bridge was constructed, and provides some wonderful views of the river.