By Ingri d'Aulaire, Edgar Parin d'Aulaire
The big, classic collection of the Greek myths — every Titan, god, and hero gathered in one place, told in grand old-fashioned prose with the famous chalky illustrations a lot of grown-ups grew up on.
It opens at the very beginning — Mother Earth, the Titans, Cronus swallowing his own children — and works its way forward through all twelve Olympians, the lesser gods, and the mortal heroes like Perseus and Theseus. By the last page your child has the whole map of Greek mythology in their head, not just the famous bits. The telling is stately and old-fashioned, and the dreamy stone-lithograph pictures look like nothing in a modern book.
It's the most demanding read on the trail and also the most complete, which is why it sits last. The prose is formal and the vocabulary is a genuine stretch, so a child who's climbed up through the funnier, lighter books arrives here ready for a real classic. It's built as one myth after another, so a fluent reader can graze it for years and keep coming back to it as the book they check when they've forgotten how a story goes. Finish it and your child actually knows the myths rather than only the famous ones.