Grimmauld Place, Number 12

• Type: Residence, Ancestral Home, Headquarters
• Location: Islington, London, England
• Owner/Residents: Formerly the Black Family; later, Sirius Black, then Harry Potter. Residents included Kreacher, members of the Order of the Phoenix, Harry Potter, Ron Weasley, and Hermione Granger.
• Key Features: Unplottable; protected by a Fidelius Charm; filled with Dark Arts artifacts and unpleasant magical traces; decorated with serpent motifs; perpetually gloomy and dusty.

Number twelve, Grimmauld Place is the ancestral home of the Black Family, a pure-blood wizarding family known for its obsession with blood purity and practice of the Dark Arts. The house is located in a Muggle neighborhood in London, rendered invisible and Unplottable to those not privy to its secret. To the uninitiated, the houses on the street appear to jump from number eleven to thirteen. The house itself is a tall, narrow, and grimy building that reflects the dark history of its former occupants. The interior is perpetually dark and dusty, with the smell of damp and decay. Much of the decor is themed around serpents, a nod to the family's association with Slytherin house. The main hallway features peeling wallpaper, threadbare carpet, gas lamps, a large umbrella stand made from a troll's leg, and a row of shrunken house-elf heads mounted on plaques along the staircase. A life-sized, enchanted portrait of Walburga Black, Sirius Black's mother, is located in the hall; it shrieks and yells insults whenever it is disturbed by loud noises or the presence of those she deems unworthy, such as “mudbloods” or “blood traitors”. The house fell into disuse and deep neglect after the death of Walburga Black. Her son, Sirius Black, who had run away from home as a teenager, inherited the property. Despite his hatred for the place, he offered it to Albus Dumbledore to be used as the headquarters for the reconstituted Order of the Phoenix during the Second Wizarding War. Dumbledore cast a Fidelius Charm upon it, making himself the Secret-Keeper to ensure its security. After Sirius's death, the house and its resident house-elf, Kreacher, were bequeathed to Harry Potter.

Grimmauld Place is introduced in Harry Potter and the Order of the Phoenix as the secret headquarters for the Order of the Phoenix. Harry Potter is brought here after being rescued from his relatives' home and spends the remainder of the summer within its walls. The house serves as a place of both refuge and confinement, particularly for Sirius Black, who is unable to leave due to being a wanted fugitive. The gloomy atmosphere of the house mirrors the dark times and the emotional turmoil of the characters, especially Harry's frustration and Sirius's depression. In Harry Potter and the Deathly Hallows, the house becomes a temporary sanctuary for Harry, Ron Weasley, and Hermione Granger after they escape from the attack at the wedding of Bill Weasley and Fleur Delacour. While hiding there, they uncover crucial information about Regulus Arcturus Black and his quest to destroy Lord Voldemort's Horcrux, the Slytherin's Locket. The trio is forced to abandon Grimmauld Place permanently after Harry inadvertently breaks the Fidelius Charm's protection by speaking the location's name, allowing the Death Eater Yaxley to grasp hold of Hermione as she Disapparated, thereby revealing the secret to the enemy.

• Entrance Hall: A long, gloomy hall containing the troll's leg umbrella stand and the permanent-sticking-charmed portrait of Walburga Black.
• Basement Kitchen: A cavernous, stone-walled room that serves as the primary meeting and dining area for the Order of the Phoenix. It contains a large wooden table, a great fireplace, and numerous cupboards.
• Drawing Room: Located on the first floor, this high-ceilinged room has an air of faded grandeur. It features a large tapestry depicting the Black Family Tree, which has had members like Sirius Black and Andromeda Tonks blasted off it. A locked writing desk in this room was found to contain a Boggart.
• Bedrooms: The house has numerous bedrooms, most of which are dusty and unwelcoming.
  • Sirius's Bedroom: In stark contrast to the rest of the house, Sirius Black's old room is decorated with Gryffindor banners, posters of Muggle motorcycles and bikini-clad girls, and a permanent sticking charm-affixed photo of the four Marauders.
  • Regulus's Bedroom: Formerly belonging to Regulus Arcturus Black, this room is decorated with Slytherin colors and features newspaper clippings about Lord Voldemort pasted on the walls. It is here that Harry finds the fake Horcrux locket left by R.A.B..

• The name “Grimmauld” is a pun on the phrase “grim old place,” which accurately describes the house's atmosphere and condition. (J.K. Rowling interview)
• In the film adaptation of Harry Potter and the Order of the Phoenix, the house is shown to magically squeeze its way into existence between numbers 11 and 13, pushing the Muggle houses aside to reveal itself. (film)