Dungeons

The dungeons of Hogwarts Castle are located under the school, and it is colder there than in the main castle. The Potions classroom is located in the dungeons, as is the entrance to the Slytherin common room and dormitories.

Behind the scenes

In the video game adaptation of Harry Potter and the Philosopher's Stone, the dungeon is very dirty, filled with spiders and loads of gooey ponds, it also shows that it is a long walk to the classroom from when you first enter the Dungeons. The dungeons classroom is really just downstairs when you enter the Dungeons.
Elizabeth Burke's portrait was hanging in these dungeons in the 1995–1996 school year, connecting it with the Entrance Dungeon.
Professor Basil Fronsac's portrait was hanging in these dungeons in the 1996–1997 school year, connecting it with the Grand Staircase.