On the north wall of the antechamber is the stairway down to the burial chamber , a vast quadrangular room covering a surface area of about , its astronomical ceiling supported by four pillars entirely decorated .
On the north wall of the antechamber is the stairway that goes down to the burial chamber . This is a vast quadrangular room covering a surface area of about 90 m2 , the astronomical ceiling of which is supported by four pillars entirely covered with decoration .