This large hall is where Nearly Headless Nick always celebrates his death-day. This is also used for some dances and mini parties within houses.

The Potions Classroom is where Potions classes are taught. The classroom is squared-sized, very large, with large tables and windows. In the corner resides a stone basin used to wash students' hands and ladles.

A small, rectangular storage room located directly across from the potions room. It contains many of the potion master's personal potions and ingredients and doubles as a favored hiding place among affectionate students.

The Head of Slytherin sleeps and works here. It is a square room with a door at the rear, leading to the Head's bedroom.

Located behind a wall in the castle cellars, the dungeon-like room extends partway under the lake, giving the light in the room a green tinge.

This common room emphasises comfort, said to be "the cosiest common room of them all". It is at one floor below the ground and is very sheltered from the elements, generally allowing students to sleep easier than those in the towers and dungeons.

The kitchens are located directly under the Great Hall under a portrait of a bowl of fruit. One may gain access by tickling the pear.