Over a thousand years before the events of Harry Potter, four of the brightest witches and wizards of the time came together and decided to build Hogwarts School of Witchcraft and Wizardry. These four founders were Salazar Slytherin, Godric Gryffindor, Helga Hufflepuff, and Rowena Ravenclaw and what they accomplished together was no small task. They built the school from nothing and did it while witches and wizards were widely persecuted.

Even though they didn’t always see eye-to-eye, the Hogwarts founders worked together in harmony for years; however, the discord between them grew and the Hogwarts Four became the Hogwarts Three when Slytherin decided to make his dramatic exit. You might assume that Slytherin was the only founder with a dark past, with his preference for pure-bloods and his plot to unleash a bloodthirsty basilisk on unsuspecting students, but each of the founders made some regrettable decisions in their time. Even Hufflepuff, who was known for her altruism and kindness, had some skeletons in her closet. Despite their misdeeds, their legacies live on through their houses and the beloved school they built together.

Here are 15 Things You Didn’t Know About The Founders of Hogwarts.

15. The Sorting Hat Thinks The Founders Were Wrong To Divide Students

Sorting Hat Draco Harry Potter: 15 Things You Didnt Know About The Founders of Hogwarts

In what seemed like an uncharacteristically somber speech in The Order of the Phoenix, the Sorting Hat had a new song in which it told the tale of the four founders. In the song, the Hat speaks of how close Slytherin and Gryffindor were, a friendship that was only matched by the bond between Hufflepuff and Ravenclaw.

The song implies that when Hogwarts was originally founded, the founders were not selective when it came to choosing the type of students they would teach. It was only after Ravenclaw, Slytherin, and Gryffindor became more picky about who they allowed in their houses that the harmony between the four houses began to deteriorate. According to the Hat, only after this division did the houses turn on each other. Though the Hat proceeds to sort the students, saying that it is condemned to do so, it also says that splitting the students up is wrong.

14. Slytherin Intended To Use The Chamber Of Secrets As A Classroom

Chamber of Secrets Harry Potter: 15 Things You Didnt Know About The Founders of Hogwarts

Despite what you think about Salazar or his house, you have to be a little impressed that Slytherin managed to create a massive chamber without his fellow founders knowing about it. The best wizards and witches of the time ran Hogwarts when he was building it, but presumably none of the other founders suspected anything, despite the growing rift between them.

Interestingly, Slytherin’s original intended use for the chamber was a little less sinister (though not by a lot). The Chamber of Secrets entry on Pottermore suggests that Slytherin may have constructed the chamber to be used as a “place in which to instruct his students in spells of which the other three founders may have disapproved,” which basically means Dark Arts spells. While the chamber looks like it was made to accommodate a basilisk, it bears noting that the design of the chamber makes it ideal for formal dueling.