Article: The Queen addressed the United Nations for a second time in 2010, again in her capacity as Queen of all Commonwealth realms and Head of the Commonwealth. The UN Secretary General, Ban Ki-moon, introduced her as "an anchor for our age". During her visit to New York, which followed a tour of Canada, she officially opened a memorial garden for the British victims of the September 11 attacks. The Queen's visit to Australia in October 2011 – her sixteenth visit since 1954 – was called her "farewell tour" in the press because of her age.

Now answer this question: When was Elizabeth's farewell visit to Australia?
October 2011