I was seven, and I remember it well:
The Lion, the Witch and the Wardrobe by C.S. Lewis
This book was, and is, magic. It made me love reading, and it was my introduction to my favorite genre: fantasy. It’s still one of my favorite books. I am of the firm belief that the correct order in which to read the series is chronological by publication date, making this one the first– don’t pay attention to those pesky numbers on the newer editions! Trust me, things are much more interesting with a fractured timeline; there are so many more “aha!” moments.
Curious about the rest of my answers? Find a list of them here.