Hogwarts Turris Magnus is among the largest towers of Hogwarts Castle. It stands next to the Viaduct Entrance, overlooking the Suspension Bridge and the Training Grounds. It has a semi-circular shape. The tower is home to Minerva McGonagall's office on the first floor, the third floor and Serpentine Corridors, Classrooms 3C and 7A, Lost Wands store and the Ghoul Studies classroom on the third. A staircase runs through the centre of the tower.