Belgian and Dutch Royals at the Frankfurter Buchmesse on October 18, 2016 in Frankfurt am Main, Germany.

 Queen Mathilde inaugurate with King Willem-Alexander of Netherlands (not pictured) the netherlands-flemish pavillon of the Frankfurter Buchmesse.

King Philippe and Queen Mathilde inaugurate with King Willem-Alexander of Netherlands (not pictured) the netherlands-flemish pavillon of the Frankfurter Buchmesse.

Queen Mathilde inaugurate the netherlands-flemish pavillon of the Frankfurter Buchmesse. 

Belgian Queen Mathilde and King Philippe pose ahead of the opening of the Dutch-Flemish pavilion, on the eve of the official kick-off of the Book Fair on October 18, 2016 in Frankfurt am Main. Belgiun and the Netherlands are the official guest of this year's edition.

Belgian Queen Mathilde and King Philippe attend the opening of the Dutch-Flemish pavilion, on the eve of the official kick-off of the Book Fair on October 18, 2016 in Frankfurt am Main. Belgiun and the Netherlands are the oficial guest of this year's edition.

Belgian Queen Mathilde and King Philippe attend the opening of the Dutch-Flemish pavilion, on the eve of the official kick-off of the Book Fair on October 18, 2016 in Frankfurt am Main. Belgiun and the Netherlands are the official guest of this year's edition.

from left. Queen Mathilde, King Philippe of Belge, King Willem Alexander of Netherlands, Martin Schulz and Jet Bussemaker, minister of culture pose for a photo before the opening ceremony of the 2016 Frankfurt Book Fair (Frankfurter Buchmesse) on October 18, 2016 in Frankfurt am Main, Germany. The 2016 fair, which is among the world's largest book fairs, will be open to the public from October 19-23.

from left. Queen Mathilde, King Philippe of Belge, King Willem Alexander of Netherlands, Martin Schulz and Jet Bussemaker, minister of culture pose for a photo before the opening ceremony of the 2016 Frankfurt Book Fair (Frankfurter Buchmesse) on October 18, 2016 in Frankfurt am Main, Germany.

(L) King Willem Alexander of Netherlands, Queen Mathilde, King Philippe of Belge arrive to the opening ceremony of the 2016 Frankfurt Book Fair (Frankfurter Buchmesse) on October 18, 2016 in Frankfurt am Main, Germany. The 2016 fair, which is among the world's largest book fairs, will be open to the public from October 19-23.

from left. Queen Mathilde, King Philippe of Belge, King Willem Alexander of Netherlands, Martin Schulz and Jet Bussemaker, minister of culture pose for a photo before the opening ceremony of the 2016 Frankfurt Book Fair (Frankfurter Buchmesse) on October 18, 2016 in Frankfurt am Main, Germany. The 2016 fair, which is among the world's largest book fairs, will be open to the public from October 19-23



Dutch King Willem-Alexander (L) and Belgium's King Philippe exchange books in Frankfurt am Main, western Germany, on October 18, 2016 after the opening ceremony of the Frankfurt Book Fair. 

Queen Mathilde and King Philippe of Belgium (R) at the opening ceremony of the 2016 Frankfurt Book Fair (Frankfurter Buchmesse) on October 18, 2016 in Frankfurt am Main, Germany.

(L-R) King Willem-Alexander of Netherlands and King Philippe of Belgium at the opening ceremony of the 2016 Frankfurt Book Fair (Frankfurter Buchmesse) on October 18, 2016 in Frankfurt am Main, Germany.

(L-R) King Willem-Alexander of Netherlands, Queen Mathilde and King Philippe of Belgium at the opening ceremony of the 2016 Frankfurt Book Fair (Frankfurter Buchmesse) on October 18, 2016 in Frankfurt am Main, Germany. 

(L-R) King Willem-Alexander of Netherlands, Queen Mathilde and King Philippe of Belgium at the opening ceremony of the 2016 Frankfurt Book Fair (Frankfurter Buchmesse) on October 18, 2016 in Frankfurt am Main, Germany.

Belgian Queen Mathilde and King Philippe pose ahead of the opening of the Dutch-Flemish pavilion, on the eve of the official kick-off of the Book Fair on October 18, 2016 in Frankfurt am Main.