London is composed of two ancient cities - the City of London, which is the original Roman settlement and financial center, and the City of Westminster, where Parliament and government offices are located. Some of London's most famous landmarks include Buckingham Palace, Big Ben, London Eye, Piccadilly Circus, St. Paul's Cathedral, Tower Bridge, Trafalgar Square, and The Shard. London is also home to numerous museums, galleries, libraries, and over 40 West End theatres.