The door to the main building of the keep opens with a creaking sound, inside the adventurers can see a corridor with an ancient staircase at the end, leading up into the open sky, the top part of it broken and ruined, much like the ceiling. As could be seen from the outside, the floor above does not exist anymore. Rubble is scattered everywhere.
There are three doors, which are still intact, leading deeper inside. Being reasonably sure, that the undead pose no threat to them currently, the party checks each of them in turn.
Behind the western door, they find a room that lies in complete ruin, similar to the barracks. There must have been beds here, maybe another guard's quarters. About a dozen undead guards are positioned here, lined up along the walls. They don't even react to the opened door. There is another door across the chamber, leading to the north.
To the east there is the old armory. Some of the weapon and armor racks are still intact, but the wood is weak and rotten. Broken weapons and shields litter the floor. Another door exits from here, into western direction.
Finally, the door to the north opens into a small chapel. The two other doors from the guard's quarters and the armory also lead here, as can be seen now. The chapel room extents about ten feet beyond the armory into the northern direction, it must connect directly with the outer walls of the keep. Sunlight beams through cracks in the ceiling and sheds light onto the altar, which seems to be intact still. The rest of the room is in a serious state of disrepair, much like the keep as a whole. A blackened and burnt-out husk of an orc lies in the center of the room, long dead, next to it a rusty sword and a wooden shield.