LUXEMBOURG - MAY 11:  Catherine, Duchess of Cambridge (L) with Princess Stephanie of Luxembourg visit the Grand Duke Jean Museum of Modern Art (MUDAM) where she will view exhibitions by British artists Sir Tony Cragg and Darren Almond during a one day visit on May 11, 2017 in Luxembourg. The Duchess is participating in the official commemoration of the 1867 Treaty of London and will attend a series of engagements to celebrate the cultural and historic ties between the UK and Luxembourg.  (Photo by Samir Hussein/WireImage)