The Grand Staircase (also called the Marble Staircase) is a massive structure in Hogwarts that is located in the Grand Staircase Tower. It is mainly used to access each floor in the castle, including the Basement and Dungeons. There are hundreds of portraits on the walls of the Grand Staircase Tower and the paintings have been known to jump around from frame to frame. Some of the portraits reveal hidden/secret passageways within the school and are quite hard to find. The multiple staircases move from one platform to another in a sequence that ends at the seventh floor. The moving staircases came as an idea by Rowena Ravenclaw, who was one of the founders of Hogwarts.