Realencyclopädie der classischen Altertumswissenschaft (RE) is a very big book full of information about ancient Greece and Rome, kind of like an encyclopedia. It has almost 100 volumes!
The people who made this book were very smart and knew a lot about ancient history, like what people wore, what they ate, how they lived, and what they believed.
If you have a question about ancient Greece or Rome, you can look it up in this book and find the answer. It's like having a really wise friend who knows everything about that time in history.
However, because it is so big and has so much information, it might be difficult for a 5-year-old to read all of it. But, it is a great resource for older kids and adults who want to learn more about the fascinating world of the ancient Greeks and Romans.