A long time ago, a secret corridor on the third floor led from the statue of a humpbacked witch all the way to Honeydukes in Hogsmeade. If one still knew the password that caused the witch to reveal the passageway, one might be able to convince her to move an inch or two...

But even then, the passageway is firmly blocked off and sealed. The only thing this witch is good for is they tiny hiding spot she reveals if a person can get her to budge.