BERLIN, GERMANY - JULY 19:  Catherine, Duchess of Cambridge and Prince WIlliam, Duke of Cambridge visit The Brandenburg Gate on day 3 of their Royal Tour of Poland and Germany on July 19, 2017 in Berlin, Germany.  (Photo by Karwai Tang/WireImage)
BERLIN, GERMANY - JULY 19:  Princess Charlotte of Cambridge arrives at Berlin military airport during an official visit to Poland and Germany on July 19, 2017 in Berlin, Germany.  (Photo by Samir Hussein/WireImage)
British Prince William, Duke of Cambridge joined by his wife Catherine, The Duchess of Cambridge are seen walking among the cement blocks at  Berlin's Holocaust Memorial on July 19, 2017. 
(Photo by Omer Messinger/NurPhoto via Getty Images)
BERLIN, GERMANY - JULY 19:  (NO UK SALES FOR 28 DAYS FROM CREATE DATE)  Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge visit Strassenkinder, a charity which supports young people from disadvantaged backgrounds  during an official visit to Poland and Germany on July 19, 2017 in Berlin, Germany.  (Photo by Pool/Samir Hussein/WireImage)
BERLIN, GERMANY - JULY 19:  Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge attend The Queen's Birthday Party at the British Ambassadorial Residence on the first day of their visit to Germany on July 19, 2017 in Berlin, Germany. The royal couple are on a three-day trip to Germany that includes visits to Berlin, Hamburg and Heidelberg.  (Photo by Matthias Nareyek - Pool/Getty Images)