Gryffindor girls’ dormitory

The girl’s dormitory is accessible from the Gryffindor common room, up a spiral staircase (OP17).

Girls are allowed to visit the boys’ dormitory, but the boys are not allowed in the girls’ dormitory (OP17). If a boy attempted to enter, the steps would melt “together to make a long, smooth stone slide like a helter-skelter” (OP17). Hermione says it explains in “Hogwarts: A History” that “it’s an old-fashioned rule” and “the founders thought boys were less trustworthy than girls” (OP17).