Diamond Jubilee of Queen Elizabeth II marking the 60th anniversary of her accession to the Thrones of the United Kingdom, Canada, Australia & New Zealand (as well as the 60th anniversary of her becoming Head of the Commonwealth).

Elizabeth II (Elizabeth Alexandra Mary; born 21 April 1926) is the queen regnant of sixteen independent sovereign states known informally as the Commonwealth realms: the United Kingdom, Canada, Australia, New Zealand, Jamaica, Barbados, the Bahamas, Grenada, Papua New Guinea, the Solomon Islands, Tuvalu, Saint Lucia, Saint Vincent and the Grenadines, Belize, Antigua and Barbuda, and Saint Kitts and Nevis. She holds each crown separately and equally in a shared monarchy, as well as acting as Head of the Commonwealth, Supreme Governor of the Church of England, and Head of State of the Crown Dependencies. As a constitutional monarch, she is politically neutral and by convention her role is largely ceremonial
http://en.wikipedia.org/wiki/Elizabeth_II_of_the_United_Kingdom