The Great Hall
Vast chamber with an enchanted ceiling that mirrors the sky outside. Four long tables for the four houses. Closest to the doors from the Entrance Hall is Slytherin, then Ravenclaw, Hufflepuff, and next to the far wall, Gryffindor (this order may possibly be reversed, depending on how you orient the room to the entrance hall). The teachers sit at the High Table, a table on a raised platform at the front of the room. A door behind the staff table allows a person to enter the Great Hall from outside without going through the main entrance.