Twenty years ago, the first book in the Harry Potter series was published. Now, two decades, seven books, eight films and various offshoots later, its filming locations are just as popular and the stories continue to resonate across generations. What is it about this magical adventure that’s captivated the world?

On June 26, 1997, a children’s book called Harry Potter and the Philosopher’s Stone by JK Rowling hit the shelves. It’s hard to believe, but this eventual bestseller had an initial print run of just 500 copies. Now, the Harry Potter series has sold over 450 million copies all over the world—at last count.

Little did anyone know, least of all the publishers Bloomsbury, what a success it would be. That not only would the books be turned into films starring some of the world’s most respected actors and launch the careers of Daniel Radcliffe and co, that prequels and sequels would follow, but that an entire theme park—the Wizarding World of Harry Potter in Orlando—would be constructed around the magical world the books inhabit.