The First-Floor Girls' Toilets on the night the Troll destroyed it
The First-Floor Girls' Toilets is where Harry, Ron and Hermione first become friends. The boys save Hermione from a Mountain Troll here.
From the Story[]
| “ | Harry and Ron save Hermione from a mountain troll in the castle’s first-floor girls’ toilet. The pair, intending on cornering the creature, accidentally trap Hermione in the bathroom with it. When they realize what they have done and rush in to save her, the trio work together to knock the troll out with its own club, and become friends from that moment forward. | ” |
In the actual book (published in 1998), the floor the toilet is on is never mentioned. Only in the movie and the video games is the location specified. In the book, Harry notes Snape is headed for the third floor. If they were on the first floor, how did Harry know Snape wasn't headed for the second floor? It would be more logical to assume the two boys were on the second floor and saw Snape head up the stairs.