The document discusses several famous landmarks in London. Trafalgar Square is the central square of London and a traditional place for people to meet, hosting various protest meetings. It features Nelson's Column. The Houses of Parliament is where the British Government sits, consisting of the Royal Apartments, House of Lords, and House of Commons. Big Ben is a large clock tower that people can visit to see the inner workings, though there are 340 stairs to climb. Tower Bridge spans the River Thames and was originally made of wood and stone before being rebuilt in concrete. Buckingham Palace is the London home of the Queen and changing of the guards takes place there.