The brothers Jacob and Wilhelm Grimm are world-famous for the many fairy-tales, the 'poetry of the people' that they collected around central Germany when they lived and worked on and off in Kassel between 1798 and 1841. Their tales have been translated into over 170 languages all over the world with over a billion editions printed, but they also worked on many other projects, most notably a dictionary that took 25 years of work just to get to the letter F. Kassel's excellent new GRIMMWELT centre, a modern 'walk-in sculpture' construction with great views from the top of the Weinberg, explores the Grimm's world of words with modern exhibition techniques. It has everything from fun interactive games for children to imaginative displays for adults. There's art too - look out for Ukrainian artist Alexej Tchernyi's 14 beautiful paper dioramas depicting the history of the dictionary, and Ai Wei Wei's mysterious coloured tree roots. German speakers will love insulting the swearword generator - which always comes back at you with a better insult. It's a marvellous place to learn about the Grimm brothers' lives, to see their UNESCO-listed personal reference books scribbled full with notes, and to take in the lovely artworks by painter and sketch artist Ludwig Emil, the third Grimm brother. Set at least two hours aside to enjoy the exhibits without hurrying. The Falada café and the rooftop terrace are open to the public.