The castle refuses a consistent floor plan

Try to draw Hogwarts and the drawing argues with you. Staircases move on the page. Towers multiply when a plot needs a new height. Films build gorgeous, specific stone that later films quietly revise. Fans who stitch these into one survey are doing devotional cartography.

A generous theory: the castle is magically inconsistent, and inconsistency is the point. A plainer theory: no single authorial map was ever in charge, and the pleasure of the place does not require one.

Either way, a diagram in a gift shop is a drawing, not a deed.

Some rooms stay put often enough to be useful: the hall, the hospital wing, the library, the grounds. Total chaos is a fan exaggeration of a flexible building.