Bismarck's letters to him are preserved in the U.S. Library of Congress, while some of King's letters are kept by the Otto-von-Bismarck-Stiftung in Friedrichsruh near Hamburg (Germany), which is a commemorative German Government Foundation in memory of the Chancellor of the German Empire (similar to the Presidential libraries in the United States).
He had arranged to be buried near Bismarck's mausoleum on his estate at Friedrichsruh, Lauenburg in present-day Schleswig-Holstein, northern Germany.