VIENNA, AUSTRIA - APRIL 05:  Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall are greeted by Federal President of the Republic of Austria Alexander Van der Bellen and First Lady Doris Schmidauer as they arrive at Hofburg Palace on April 5, 2017 in Vienna, Austria. Her Royal Highness will accompany the First Lady on a tour of the presidential apartments whilst His Royal Highness and the President hold a bilateral discussion with the Austrian and British delegations. (Photo by Chris Jackson-Pool/Getty Images)