The Shrieking Shack

The Shrieking Shack is an abandoned house in Hogsmeade. For many years, villagers thought it was haunted because they often heard screams coming from inside, and Albus Dumbledore encouraged the rumour, as he was the one who commissioned it, due to Remus Lupin's Lycanthropy. According to Nearly Headless Nick, not even the Hogwarts ghosts will enter it. The Shrieking Shack's entrance from the Hogwarts Grounds is the base of the Whomping Willow. The trick is to poke the knot in the trunk, which paralyses the tree. The secret passageway can be seen on the Marauder's map.