The museum said more than 3, 500 people from all over the world have left comments in the exhibition's visitor's book.

BBC: Richard III exhibition in Leicester has 50,000 visitors

Earlier on Tuesday, Mr Mandela signed the visitor's book at Aras An Uchtarain, the home of Irish heads of state, and then had 20 minutes of private talks with Mrs McAleese.

BBC: Mandela urges NI peace

There are eight selections, which include a look back at Road Dahl's life, a history of his publications, details of his charity The Roald Dahl Foundation, a visitor's book, a section for Teachers, Treats for kids and you can even choose to be guided around the site by one of your favourite Roald Dahl characters.

BBC: Roald Dahl web worth it