London is the capital of England and the UK, located on the River Thames. It has a long history dating back to Roman times and is famous for landmarks like Big Ben, Buckingham Palace, the British Museum, and Tower Bridge. In the 19th-20th centuries, London's fog and smoke from coal heating created thick smog, culminating in the Great Smog of 1952 that killed over 4,000 people. In response, clean air acts were passed to reduce pollution. London is also known for its parks, museums, and royal residences like Buckingham Palace.