Disused Bathroom (Fred and George's Shop)

The Disused Bathroom is a boys lavatory on the sixth floor of Hogwarts Castle which has not been used since sometime prior to 1993. In that year, Fred and George Weasley moved their shop from  a bathroom on the seventh floor to this one.

Past
The bathroom was likely created with the rest of the school by Godric Gryffindor, Salazar Slytherin, Helga Hufflepuff and Rowena Ravenclaw in Medieval times on the sixth floor near the Study of Ancient Runes Classroom. At some point, the bathroom fell into disuse and was no longer used. However, two Famous Witches and Wizards Cards were found in the toilets and a number of school robes remained on a coat peg by a bookshelf. One of the toilets was broken and another was covered in a pool of water.

Fred and George’s Shop
In 1993, Fred and George Weasley moved their shop from  a disused bathroom on the seventh floor in Gryffindor Tower to the one on the sixth floor. They placed a number of objects on trunks and shelves around the sinks and cast some sort of spell that caused only the objects that the buyer would like to purchase appear. They also used a secret passageway through a wall in the bathroom to hide the Marauder's Map. They eventually told Harry Potter and Ronald Weasley where it was and allowed them to keep the map. In 1994, it appears that Fred and George discontinued their shop in the bathroom.

Items and Products
The items sold in the bathroom included:
 * Stink Pellets
 * Dungbombs
 * Snufflifors Spell Book
 * Dark Forces: A Guide to Self-Protection
 * A number of rare Famous Witches and Wizard Cards

Appearances

 * Harry Potter and the Prisoner of Azkaban (video game) (first appearance)