Walk straight to the door behind Diana Huntress and exit the Caryatids room. Turn immediately to your right and then to your left. Climb the stairs (approximately sixty steps) to the first floor of the Sully Wing. Turn right to enter the rooms dedicated to Etruscan and Roman Antiquities. This is Room N°661. Go through this room and the next one (Room N° 662) to reach Room N° 663. The Cerveteri sarcophagus is towards the centre of the room, slightly to your right.