Australia's Prime Minister Malcolm Turnbull (R) and his wife Lucy (L) look on as Dutch King Willem-Alexander (2nd R) and Queen Maxima sign the visitors book at Parliament House in Canberra on November 2, 2016. 
The Dutch royals are in Australia to mark the 400th anniversary of explorer Dirk Hartog's landing in Western Australia and the unveiling of Hartog's plate, which is the oldest existing relic of European exploration in Australia. / AFP / POOL / MICK TSIKAS        (Photo credit should read MICK TSIKAS/AFP/Getty Images)