At least some content in this article is derived from information featured in Harry Potter: Hogwarts Mystery. Spoilers will be present within the article.
"This book is rich with detail about the history of Hogwarts School of Witchcraft and Wizardry. "
The book was written by Bathilda Bagshot and published in or before 1991. A copy was seen on a windowsill in Hogwarts during that year. The book was also very popular in Harry Potter's second year at Hogwarts, when every copy was checked out of the library due to the reopening of the Chamber of Secrets.
The book's original hand-written manuscript is stored in one of the Hogwarts Library's annexes, and can be only read by special appointment. However, students and staff may admire its ornate cover from a distance.[3]
Hermione's favourite book
It was Hermione Granger's favourite book and she often referred to it on many things concerning Hogwarts School of Witchcraft and Wizardry. Three of the things that she brought up are the Great Hall's enchanted ceiling that shows the weather outside, the fact that one cannot apparate or disapparate on Hogwarts grounds and the fact that electronic devices do not work within the grounds.
The book's removal from the Hogwarts Library when the Chamber of Secrets was opened caused Hermione great frustration, as despite her fondness for the book, she had left it behind that year due to lack of space because of the many texts assigned by Gilderoy Lockhart. However, Hermione shows slight frustration with the book when scathingly renaming the book in her fourth year because it does not mention the use of house-elves at Hogwarts, even going so far as to suggest a couple of alternative titles for it: A Revised History of Hogwarts and A Highly Biassed and Selective History of Hogwarts Which Glosses Over the Nastier Aspects of the School.
In 1997, Hermione considered this book as she was sorting supplies for their mission to find Horcruxes. It was one of the books she decided to bring with them, stating that she "wouldn't feel right" if she didn't have it.
Information
Known information included
Hermione Granger often quotes from this book. Some of the things she learns about Hogwarts from the book are that:
The ceiling of the Great Hall is bewitched to look like the outside sky.[4]
Hogwarts is hidden to Muggles. If a Muggle looks at it, they see an old ruin with a sign saying: "DANGER, DO NOT ENTER, UNSAFE".
In 1792, when a cockatrice went loose during one of the Triwizard Tournament tasks, the heads of the three schools, including one from Hogwarts, were injured by the deadly creature.
Muggle technology, such as mobile phones and laptops, cannot be used within the grounds of Hogwarts.
Boys are not allowed in the girls' dormitories; if they try to enter the stairs turn into a slide.[5]
Known information not included
The presence of house-elves working at the school in in kitchens.
The Sorting ceremony, or at least not explict details of it, as Hermione Granger was unaware of what the ceremony entailed beforehand despite reading the whole of the book.
It is unlikely that the Room of Requirement is mentioned, otherwise Hermione Granger and not Dobby would have suggested using this room for use by Dumbledore's Army.
J. K. Rowling was asked in an interview if Harry and Ron would ever read the book. She replied: "Never. It’s a gift to me, because all my exposition can be dressed up as, 'When are you going to read it?' So Hermione fills in the reader as well, so I could never let them read it."[6]
