God Save the Queen (the National Anthem of the United Kingdom)
God Save the Queen is one of the most well-known and most heard national anthems.
The piano version by Easypianoscores.com is arranged like a choral for beautiful, choir-like sound. Throughout the piece, there is not too difficult three-voice polyphony (2 voices in the right hand and one in the left).
In addition to serving as a national anthem, the theme has been used by at least 140 (!) composers for variations or other works; these composers include L. van Beethoven, Joseph Haydn, Johannes Brahms.