Room Of Requirement

"It is a room that a person can only enter when they have real need of it. Sometimes it is there, and sometimes it is not, but when it appears, it is always equipped for the seeker's needs"

—Dobby explaining to Harry Potter the abilities of the Room of Requirement

The Room of Requirement, also known as the Come and Go Room, was a secret room within Hogwarts Castle, that only appears when a person is in great need of it.

The room is thought to have some degree of sentience, because it transforms itself into whatever the witch or wizard needs it to be at that moment in time, although there are some limitations. For example, it cannot create food, as that is one of the five Principal Exceptions to Gamp's Law of Elemental Transfiguration. It is believed that the room is Unplottable, as it does not appear on the Marauder's Map, nor do its occupants, although this could simply be because James Potter, Remus Lupin, Sirius Black, and Peter Pettigrew never found the room.

Location
"It's a proper hideout, as long as one of us stays in here, they can't get at us, the door won't open. It's all down to Neville. He really gets this room. You've got to ask it for exactly what you need — like, "I don't want any Carrow supporters to be able to get in — and it'll do it for you! You've just got to make sure you close the loopholes! Neville's the man!"

—Seamus explaining the Room of Requirement

Hall of Hexes

The room is located on the seventh floor in the left corridor of the Hogwarts castle and has a hidden entrance opposite the tapestrydepicting the attempt of Barnabas the Barmy to teach trolls ballet.[1]The way to open the room is to walk past it three times thinking about what you need, and the door will appear.

It is advised that the users of this room be very specific about what they are looking for, as it has been shown that other people can enter the room and see what the occupant is doing if they know how the room is being used. The Inquisitorial Squadfound the hideout of the D.A. in 1996 by knowing that the D.A. was in the room at the time. Neville Longbottomused this knowledge to create his hideout, as he specifically asked that the hideout be made unavailable to those who supported Alecto and Amycus Carrow.[3]

Dumbledore's mention
The first mention Harry Potter heard of this room was in 1994, when Albus Dumbledore told Igor Karkaroff of his discovery of a room full of chamber pots when he needed to go to the toilet. However, he was unable to find the room again later like many of those who stumble across the room.

Dumbledore's Army
Dobby: "Dobby knows the perfect place, sir! Dobby heard tell of it from the other house-elves when he came to Hogwarts, sir. It is known by us as the Come and Go Room, sir, or else as the Room of Requirement!"

Harry Potter: "Why?"

Dobby: "Because it is a room that a person can only enter when they have real need of it. Sometimes it is there, and sometimes it is not, but when it appears, it is always equipped for the seeker's needs."

— Dobby telling Harry Potter about the Room of Requirement

The Room of Requirement providing the D.A.with something to practise spells on

In 1995, Harry Potter asked Dobby if he knew of a place where Dumbledore's Army could safely meet. Dobby told Harry of what the house-elves called the "Come and Go Room" or "Room of Requirement", which he had used to treat Winky after she had gotten drunk on Butterbeer, as the room filled with antidotes to butterbeer and an elf-sized bed for Winky to sleep off her inebriation. He also said that Argus Filch had found extra cleaning supplies in the room. During the first D.A. meeting, Fred and George Weasley revealed that it had once taken the form of a broom cupboard which they had used to hide from Filch. Previously Dumbledore had also mentioned the Room of Requirement.

Harry instructs the D.A. members on the Disarming Charm

Dumbledore's Army used the room as their headquarters and practise area. Among the items provided by the room for the D.A. were Dark Detectors and shelves of helpful books such as A Compendium of Common Curses and Their Counter-Actions, The Dark Arts Outsmarted, Self-Defensive Spellwork, and Jinxes for the Jinxed.[2]Around Christmas, which was the last meeting before the break, Harry was cornered by Cho Chang under some mistletoe and the two shared a kiss. They were eventually discovered by the Inquisitorial Squad; due to the Squad wanting evidence, the Room provided the meeting room and the list of members.

Second Wizarding War
Main article: Second Wizarding War

The Room of Requirement as a hideout for Hogwarts students in 1998

During the 1997-1998 school year, Neville Longbottom and several other students used the room as a hideout to escape the wrath of the new Death Eater professors, the Carrows. The problem was the lack of food, as it was one of the exceptions to Gamp's Law of Elemental Transfiguration. So the hideout adapted by adding an eighth passage into Hogsmeade, connected to the Hog's Head pub, whose owner, Aberforth, provided food. Also, this advantage allowed members of the Order of the Phoenix to enter the school to help fight off Lord Voldemort's attack, without setting off the Caterwauling Charm on the village.[3]

History
"I virtually lived in the Room of Hidden Things all last year, I know how to get in."

—Draco Malfoy to Harry Potter regarding the room of hidden things[src]

After Tom Riddle resurfaced as Lord Voldemort and had his second request of becoming Hogwarts' Defence Against the Dark Arts teacher denied by Dumbledore, Voldemort managed to sneak Rowena Ravenclaw's Diadem into the room, as a means to hide one of his Horcruxes. Unlike the others, he did not have time to set up many powerful spells to protect it due to time constraints, but believed that he was the only one who knows of the room's existence, and that nobody would look for it.

In his sixth year, Draco Malfoy spent the majority of his days within this room, fixing the Vanishing Cabinet that he moved from the school's hallway, in order to smuggle Death Eaters in and help him assassinate Dumbledore. The repair took most of the year, as Draco spent much time inside the room, and had his friends Vincent Crabbe and Gregory Goyle remain outside in disguise to drop something onto the ground should anyone approach, to warn Draco not to come out.

Harry using the Room of Hidden Things to hide the Half-Blood Prince's copy of Advanced Potion-Making

Harry used the room in his sixth year to hide the Half-Blood Prince's copy of Advanced Potion Making. He found that many other students had used the room to hide a multitude of other objects, including the Vanishing Cabinet. Inside the cabinet in which he hid the book, Harry found a cage that contained the skeleton of something that had five legs.[5]

Also in Harry's sixth year, Professor Trelawney attempted to use the room to hide her sherry bottles, but Draco Malfoy threw her out. Draco was using the room to repair the Vanishing Cabinet so he could smuggle Death Eaters into the castle via a matching Vanishing Cabinet in Borgin and Burkes. They did in fact use the room to infiltrate the castle in 1997.

The Room of Hidden Things became inaccessible whenever the Room of Requirement was used for another purpose. As a result, during the Battle of Hogwarts, when the room was being used to provide passage to Hogsmeade and as a sanctuary, it had to be vacated of all people and "reset" before the Room of Hidden Things could once again be accessed.

Protection
The Room of Requirement in 1998

The Room of Hidden Things may have had a special protection that prevented a Summoning Charm being used in it,[6] meaning students had to physically find what it was they were looking for. This was the case when Hermione attempted to summon Rowena Ravenclaw's Diadem, but failed, although this may be because the diadem was a Horcrux. She, Ron and Harry had to go searching for it instead. However, this protection may have been placed by Voldemort specifically for the diadem, as he took similar precautions for his locket Horcrux. Tom Riddle believes that he, and only he, is the only person that ever discovered the deepest secret in Hogwarts. He never expected Harry to discover this chamber. Additionally, even House-Elves cannot Apparate into the room, meaning they have to know what to ask the room to become into in order to access it.

While Harry discovered Draco is using this chamber to progress his plan, he could not make the room appear for him to see what the young Death Eater was up to, no matter what variation of thinking he used, thus giving Draco the privacy he requested.

Skirmish in the Room of Requirement
Main article: Skirmish at the Room of Requirement

The Fiendfyre destroying much of the contents of the Room of Requirement

Later that same year, during the Battle of Hogwarts, it was used as an evacuation route to move the students away from the dangers that followed. Later, Harry realised that Rowena Ravenclaw's Diadem, one of Voldemort's Horcruxes, was hidden in the Room of Requirement, as he has seen it in his sixth year while hiding his Potions book and had even picked it up without realising what it was.

As noted above, as long as the room was being used to maintain the passage to Hogwarts, the Room of Hidden Things couldn't be accessed. Harry, Hermione, and Ron cleared the room and accessed the Room of Hidden Things, where they were ambushed by Draco Malfoy, Vincent Crabbe and Gregory Goyle. Crabbe let loose cursed fire that destroyed the Horcrux and many other objects, killing himself in the process. The entire room was turned into a sea of flames, and Ron wondered if the Room of Hidden Things could be accessed again due to the possibility of it being destroyed.

Items hidden inside
Harry Potter saw many things that other students had hidden in the room, including:

Some of the items Harry has seen in the Room of Hidden Things

Some more items seen in the Room of Hidden Things
 * Broken and damaged furniture (mostly chairs, tables, & various cabinets haphazardly stacked), perhaps hidden to hide mishandled magic
 * Thousands and thousands of books (either in tottering piles or in bookcases)
 * Flying catapults
 * Fanged Frisbees
 * Chipped bottles of congealed potions
 * Corked bottles whose contents still shimmered evilly
 * What looked like dragon eggshells
 * Several rusting swords
 * A heavy, bloodstained axe
 * An enormous stuffed troll
 * The broken Vanishing Cabinet that Graham Montague had gotten shoved in by Fred and George Weasley while attempting to take points away from Gryffindor during the 1995-1996 school year. Later repaired by Draco Malfoy.
 * Hats, jewels (including a trunkful), and cloaks
 * Many cages in various sizes, including one with a 5-legged skeleton in it
 * The lost diadem of Ravenclaw, made into a Horcrux
 * The Half-Blood Prince's copy of Advanced Potion-Making
 * A chipped old bust of an ugly warlock
 * A few, heavy broomsticks
 * A record turntable that "skipped"
 * A banjo
 * A set of dominoes
 * Various metalware (including cauldrons)
 * Various trophies
 * A mask
 * Various portraits; also frames
 * Suits of armour (some disassembled)
 * Various textiles

Behind the scenes

 * In the fifth film, Neville Longbottom found the Room of Requirement.
 * In the sixth film, Harry and Ginny have their first kiss in the Room of Hidden Things, instead of the Gryffindorcommon room.
 * In the eighth film, Gregory Goyle casts the Fiendfyre curse in the Room of Hidden Things, killing himself in the process, since Vincent Crabbe was cut from the two-part film. Also, Blaise Zabini is present at the fight. However Gregory Goyle is killed by grabbing a loose chair and falling into the Fiendfyre unlike Vincent Crabbe.
 * In the Harry Potter and the Half-Blood Prince video game, the Room of Requirement can be found on the sixth floor, even though in one of the scenes in the game Harry says the room is on the seventh floor. In the fifth game, fifth film, and all the books, the room is on the seventh floor. Presumably this is because the first floor in Europe is called the second floor in the USA.
 * The Room of Requirement is the main location of the Nintendo DS version of LEGO Harry Potter: Years 1-4, despite being introduced in Harry Potter and the Order of the Phoenix.
 * In the Harry Potter and the Philosopher's Stone video game, the Room of Requirement is possibly mentioned by Albus Dumbledore, who was walking around the castle and found a room full of Chocolate Frogs. On another day, however, the room was filled with Fire Crabs.
 * In the Harry Potter and the Goblet of Fire video game, the Room of Requirement is possibly mentioned by Albus Dumbledore, who was walking around the castle and found a room full of a fine collection of chamber pots. He said that he wanted to find it again.
 * In Harry Potter and the Half-Blood Prince and Harry Potter and the Deathly Hallows: Part 2, in the Room of Hidden Things can been seen several objects from previous movies, such as:
 * Some chess pieces from the giant Wizard's Chess Set from Harry Potter and the Philosopher's Stone.
 * The Chinese lanterns used in Horace Slughorn's Christmas party in Harry Potter and the Half-Blood Prince.
 * Several flasks containing seeds and dried fruits from the Potions Classroom.
 * An Astrolabe-shaped object seen in Dumbledore's office.
 * The gramophone used in Harry Potter and the Goblet of Fire by Professor McGonagall when introducing the students to the Yule Ball, constantly skipping a disc.
 * Possibly the Mirror of Erised
 * Several glass stands seen in Remus Lupin's office in Harry Potter and the Prisoner of Azkaban.
 * Several trophies from the Trophy Room.
 * In the books, it is stated that to enter the room, a person must walk by the wall three times for the door to appear. In the film, Neville Longbottom walks by the wall only once when he finds the room.
 * There is contradictory evidence as to Dumbledore's knowledge of the Room. Though he states to Karkaroff in Goblet of Fire that he only found the room once and did not know its true purpose, Pottermore reveals that Dumbledore found the Mirror of Erised in the Room. However, it is possible that he was being facetious, as saying he later found the Room's true purpose would ruin the point of bringing it up in the first place (that he didn't know all the castle's secrets).
 * In the original script for the film adaption of Harry Potter and the Half-Blood Prince, Ginny claims to have been shown the Room of Requirement in her first year by Fred and George.[7] This cannot be considered canon, however, as Fred and George did not know of the nature of the room themselves until the Dumbledore's Army meetings in Ginny's fourth year.
 * It is unknown if the Room of Requirement can still be accessed, as the Room of Hidden Things was heavily damaged by Crabbe's Fiendfyre sealing itself once Harry, Hermione, Ron, Draco and Goyle were out.
 * In the film adaptations of Half-Blood Prince and Deathly Hallows, almost all of the objects were reused props from the previous 7 films, which included, besides the previously listed objects:
 * Some of the human-sized chess pieces
 * Various light fixtures (candle stands & candelabras, lampstands, lanterns, & chandeliers); including the red Chinese lanterns used in the Slug Club Christmas Party
 * Cabinet of flasks containing seeds and dried fruits from the Potions Classroom
 * Several glass stands seen in Remus Lupin's office
 * Some of Mad-Eye Moody's dark detectors
 * Several cups & trophies, and badges of merit from the Trophy Room
 * Astronomy-related paraphernalia: including an astrolabe from Dumbledore's office; globes, armillary spheres, & telescopes with their stands and holders in various sizes
 * statue of the first Headmaster of Hogwarts
 * Various mirrors, including one with a frame similar in appearance to the Mirror of Erised (whether it is the actual Mirror is unknown, but it did live there once)
 * Cornish Pixies
 * Hog/boar statue bearing a resemblance to the one in the Chamber of Reception
 * Statue of Gunhilda of Gorsemoor on the third floor concealing the secret tunnel towards Honeydukes Sweetshop, oddly perched on a colossal plinth
 * Dragon skeleton, which hung from the ceiling of the Defence Against the Dark Arts classroom
 * Furniture from the Divination Classroom; including the draped tables stacked on top of the other and their chairs, mounds of teacups & saucers perched in a pyramid on a table, & the crystal balls with their stands
 * Gramophones, one of them constantly skipping a disc (a reference to the "skipping record turntable")
 * Trunks & suitcases in various sizes
 * Harp
 * Projector
 * Various glassware
 * Various textiles, including curtains, rugs, & sections of tapestries
 * A pair of antlers
 * Silver skulls
 * Urns & jars
 * Stands & tripods
 * Clocks in various casements
 * small cannon
 * In LEGO Harry Potter: Years 5-7 the cabinet that contained a Boggart can be seen. Also, the Flying Ford Anglia is used to make a bridge. Additionally, a panda is burned by the Fiendfyre.