Draco turned from the scene and walked towards the huge double doors, only transfiguring the snakes back into books as the doors shut behind him. He climbed the stairs three at a time not knowing exactly where the Gryffindor entrance was but he remembered in the third year when Sirius Black had torn a portrait of a fat lady to shreds with a knife that surely marked the entrance of the tower. He also knew that it was housed in one of the three tallest towers in the castle and that one of the three was the astronomy tower so he could rule it out. Racing up the Grand staircase, he turned to jog down the long narrow corridors where no students dwindled. The first tower he checked held no such painting but he did spot the shiny wings of a Raven spread across the far wall. So he found Ravenclaw Tower then. 