The Hogwarts Dungeons

• Type: Subterranean Level / School Area
• Location: Beneath Hogwarts Castle, Scotland
• Owner/Residents: Hogwarts School of Witchcraft and Wizardry; Slytherin house students; Horace Slughorn; The Bloody Baron. Formerly resided in by Severus Snape.
• Key Features: Cold, subterranean stone corridors, lit by torches, location of the Potions classroom and the Slytherin Common Room.

The dungeons are the subterranean level of Hogwarts Castle, located beneath the Entrance Hall and reached by a flight of stone steps. They are notoriously cold and dimly lit, with a network of stone corridors that can be confusing to navigate. The atmosphere is often described as eerie or oppressive, particularly compared to the upper levels of the castle. The walls are bare stone, and the air is noticeably colder than the rest of the school, a fact Harry Potter often observes. As part of the original Hogwarts foundation, the dungeons have existed since the school's creation. They house several important rooms, including the Potions classroom, Professor Snape's former office, and the entrance to the Slytherin Common Room. The proximity of the Slytherin quarters to the Potions classroom contributed to Severus Snape's favouritism towards his own house students during his tenure as Potions Master. The corridor leading to the Hogwarts Kitchens is also located near the dungeons' entrance area.

The dungeons are the setting for many significant events throughout the series. As the location of the Potions classroom, it is where Harry Potter and his classmates spend a great deal of their academic time, often under the intimidating watch of Professor Snape and later the more amiable Horace Slughorn. Key moments in the dungeons include Harry winning the Felix Felicis, his discovery of the Half-Blood Prince's textbook annotations, and the terrifying Occlumency lessons with Snape. In Harry Potter and the Chamber of Secrets, Harry and Ron Weasley use Polyjuice Potion to disguise themselves as Slytherin students and infiltrate the Slytherin Common Room to question Draco Malfoy. In Harry Potter and the Philosopher's Stone, the Mirror of Erised is temporarily hidden in an unused dungeon classroom, and Professor Quirrell unleashes a mountain troll into the dungeons as a diversion on Hallowe'en. During the Second Wizarding War, under the control of the Carrows, the dungeons became a place of punishment. As revealed by Neville Longbottom, students who defied Voldemort's regime were often taken to the dungeons to be tortured with the Cruciatus Curse.

• Potions Classroom: The primary classroom for Potions lessons. It is described as a large, cold room with pickled animals floating in jars along the walls. The classroom contains numerous worktables and a storeroom cupboard with potion ingredients. It is connected directly to the Potions Master's office.
• Slytherin Common Room: The common room for Slytherin House. The entrance is a stretch of bare, damp stone wall in the dungeons, which opens when given the correct password. The room itself is long, low, and situated under the Black Lake, giving it a greenish, underwater glow. It is furnished with carved stone chairs, skulls, and green-lit lamps.
• Severus Snape's Office: Adjoining the Potions classroom, this was Snape's private office. It was a dimly lit room filled with shelves of jars containing disturbing specimens and potion ingredients. This office was the setting for Harry's Occlumency lessons.
• Corridors and Storerooms: The dungeons are a labyrinth of corridors and unused rooms. One such storeroom was used by Argus Filch as a place for detention, where Harry was forced to pickle rat brains. Another unused room was where Professor Quirrell briefly hid the Mirror of Erised.

• In the film adaptations, the dungeons are portrayed with a more expansive and gothic aesthetic than described in the books. The sets often feature intricate stone carvings, chains, and large, dramatic spaces that emphasize their sinister and ancient nature (film).
• According to Pottermore, the location of the Slytherin Common Room beneath the Black Lake is an intentional design feature, and its windows look out into the depths of the lake, where occupants can occasionally see the Giant Squid or other aquatic creatures swim by (Pottermore).