Muggles, witches, and wizards alike feel old: the Harry Potter series first hit bookshelves 20 years ago. Monday, June 26 marks the 20-year anniversary of the first UK printing of Harry Potter and the Philosopher’s Stone — better known as Sorcerer’s Stone across the pond.

In honor of the occasion, J.K. Rowling released a message reading, “20 years ago today a world that I had lived in alone was suddenly open to others. It’s been wonderful. Thank you.”

As the Boy Who Lived turns 20, there are a few weirder details you might have forgotten about the book that started it all. Because, as we all known, Mr. and Mrs. Dursley, of number four, Privet Drive, were not perfectly normal, thank you very much. Obviously, we’re focusing on seven weird things, because, of course, there are seven books in the Harry Potter series, seven years at Hogwarts, and seven ways Voldemort split up his evil soul.

1. There Are Two Different Versions of the Book

Although this detail does not impact the series, it’s nevertheless interesting: The first book is the only one with two different titles. The British version is Harry Potter and the Philosopher’s Stone, while the American version is Harry Potter and the Sorcerer’s Stone. The reasoning was that the publisher didn’t think Americans knew or cared what a “philosopher” was. Of course, there are minute vocabulary differences between the American and UK versions of all seven books, like “flashlight” versus “torch,” but the first book is the only area where this extends to the title, too.

Apparently, by the time the subsequent novels came out, Harry Potter’s wild popularity mitigated any concern about whether Americans knew or cared what a goblet was.

Dumbledore in the headmaster's office at Hogwarts

2. Dumbledore Has a Scar That Looks Like the London Underground

The most enduring mystery of the Potter series is not what’s up with the veil at the Department of Mysteries or what the Dementors made Dudley see that traumatized him so much. Rather, it’s why the hell Dumbledore has a scar that looks like the London Underground — a question Rowling left us hanging on. Before McGonagall and Dumbledore leave baby Harry on the Dursleys’ doorstep, McGonagall and Hagrid ask Dumbledore if he can “do something” about baby Harry’s scar. Dumbledore says, “Scars can come in handy. I have one myself above my left knee that is a perfect map of the London Underground.”

How did he get this scar? In what way does it come in handy if he can apparate and fly and, therefore, doesn’t need to use the Underground? Explain yourself, Rowling.

Sirius Black in Azkaban

3. Sirius Black Is in It

Although Sirius Black does not officially appear in the story until Harry Potter and the Prisoner of Azkaban, he’s name-dropped in the very first chapter of Sorcerer’s Stone. It only goes to show J.K. Rowling’s meticulous planning. When Hagrid rides his flying motorcycle to deliver baby Harry to Privet Drive, he explains where he got the unconventional vehicle. “Young Sirius Black lent it to me,” he says. When he leaves, he says, “I’ll be takin’ Sirius his bike back.”

As we know, he did no such thing — because poor Sirius had already been carted off to Azkaban by the time Hagrid returned to Godric’s Hollow.

Not Slytherin, eh? 

4. Hogwarts Has a Theme Song

At the end of the feast in the Great Hall, after Harry and his friends are sorted, Dumbledore leads the school in singing the Hogwarts theme song. From Chapter 7 of the novel:

“And now, before we go to bed, let us sing the school song!” cried Dumbledore. Harry noticed that the other teachers’ smiles had become rather fixed. Dumbledore gave his wand a little flick, as if he was trying to get a fly off the end, and a long golden ribbon flew out of it, which rose high above the tables and twisted itself, snakelike, into words. “Everyone pick their favorite tune,” said Dumbledore, “and off we go!”

The whimsical theme song never comes up in future books, leaving two possibilities: J.K. Rowling discarded the idea, or it’s simply sung “off-screen” in future books; the feasts are usually filled with more important events.

James and Oliver Phelps as Fred and George Weasley

5. Fred and George Throw Snowballs at Voldemort

As the end of the novel reveals, the ill-fated Professor Quirrel’s turban was hiding Voldemort. Without a concrete body, Voldemort had attached himself to the back of Quirrel’s head. This raises a delightful point about Fred and George Weasley. From Chapter 12 of the novel:

“The lake froze solid and the Weasley twins were punished for bewitching several snowballs so that they followed Quirrell around, bouncing off the back of his turban.”

“The back of his turban” is Voldemort. Fred and George totally threw snowballs at Voldemort.

The Boy Who Lived 

6. Wizards Totally Suck at the International Statute of Secrecy

The International Statute of Secrecy is a big deal. It’s the rule that keeps the Muggle world blind to the existence of the wizarding world. It’s why Hogwarts is unplottable, and Muggles who find it suddenly remember urgent appointments. It’s why the entrance of St. Mungo’s looks like a shabby department store with a weird mannequin. Violating the International Statute of Secrecy is a crime — in fact, in Fantastic Beasts and Where to Find Them, Newt Scamander almost gets executed for it. And yet, everyone violates it at the beginning of Philosopher’s Stone.

As McGonagall complains in the first chapter:

“Oh yes, everyone’s celebrating, all right,” she said impatiently. “You’d think they’d be a bit more careful, but no — even the Muggles have noticed something’s going on. It was on their news.” She jerked her head back at the Dursleys’ dark living-room window. “I heard it. Flocks of owls… shooting stars…. Well, they’re not completely stupid. They were bound to notice something. Shooting stars down in Kent — I’ll bet that was Dedalus Diggle. He never had much sense.”

Professor McGonagall 

7. Minverva McGonagall Is Fucking Psychic

Professor Trelawney’s ability to predict the future has nothing on McGonagall. From McGonagall’s words in the very first chapter:

“He’ll be famous — a legend — I wouldn’t be surprised if today was known as Harry Potter day in the future — there will be books written about Harry — every child in our world will know his name!”

20 years later, that sentiment holds true. Whether it’s the magical world or the real world, everyone knows Harry Potter’s name.

Photos via Scholastic