The space under a staircase is called a spandrel.
Bed room
Under the Staircase - 2010 was released on: USA: February 2010
The endless staircase is through a door in the Star Room, which is accessible from the Upper Hallway. Note that you need the Red Shine Sprite to get into the Star Room. There is also a shortcut to the staircase from the Main Hall. Just stand on the platform under the huge sun on the wall, then use Rocket FLUDD to blast up through the ceiling. (Rocket FLUDD is hidden in a secret room in the castle.)
Team Rocket should be there, all you have to do is read the sign next to the counter, and it should reveal a staircase.
A basement is a large room under the ground. A dungeon is a room under the ground.
It is generally safer in an interior room as in a strong tornado the exterior walls are usually the first to go. However, the absolute safest place in a tornado is a basement or cellar.
The space under the staircase is flat so that Harry Potter could live more or less "comfortably."
under my staircase....
The room under the roof is called an "Attic".
The cast of Under the Staircase - 2010 includes: Faran Ferdowsi Farsheed Ferdowsi Kimia Ferdowsi
A basement...
Spot the dragon .