The entrance hall has double oak front doors, opening to the west. It is a large, cavernous room, lit by torches, with ceiling so high it's barely visible. A wide marble staircase stands opposite the front doors and leads up to first floor. Double doors to the right lead into the Great Hall. And there are two of which lead to the Hufflepuff House and Slytherin House.

The Great Hall is a vast chamber with an enchanted ceiling that mirrors the sky outside. There are four long tables for each of the four houses. Closest to the doors from the Entrance Hall is Slytherin followed by Ravenclaw, Hufflepuff, and next to the far wall, Gryffindor. The teachers sit at the High Table, a table on a raised platform at the front of the room. There is a small antechamber that can be accessed by teachers from behind the teachers' table.

The staffroom is a long panelled room with mismatched, dark wooden chairs and a large wardrobe, sometimes inhabited by a boggart. It is located just off the Entrance Hall, and the doorway is flanked by two stone gargoyles.

A long corridor extends through the ground floor lined with many old, unused classrooms. However, students often navigate this path for easy access to the courtyard.