PARIS, FRANCE - NOVEMBER 15:  People gather and view messages written on the ground at Place de la Republique on November 15, 2015 in Paris, France. As France observes three days of national mourning members of the public continue to pay tribute to the victims of Friday's deadly attacks. A special service for the families of the victims and survivors is to be held at Paris's Notre Dame Cathedral.  (Photo by Jeff J Mitchell/Getty Images)