This was a difficult choice between this one and Pippi Longstocking. I love all of Erich Kästners books but Emil always had a special place.
It is especially fun reading it in Berlin and I will pack it for my next trip there. In case you belong to the few people who never read it: It is the story of Emil who travels to Berlin visiting his grandmother and his aunt. On his train journey all the money gets stolen that his mother had saved for Grandma. Emil knows how hard his mother worked for the money and he tries to catch the thief in Berlin. He gets help from Gustav and his friends who support him and in the end more than 90 kids are on a mission.
Kästner mainly wrote books for kids but for grown-ups I can highly recommend „Fabian“ – a really really good read.