The Inner Sanctum - my most precious chamber, Daniel. And it lies well beyond the refinery. In fact... it lies beneath the very stone of Brennenburg.
”
Alexander telling Daniel about the Inner Sanctum
The Entrance Hall, as the name suggests, is Castle Brennenburg's main entrance, and is accessed from the Old Archives. It is the third location visited and the first Hub level found in the game. Daniel's main objective here is to gain access to the Refinery by destroying a wall of fleshy residue blocking the entrance to it, in order to move further into the bowels of the castle and ultimately reach the Inner Sanctum.
The Entrance Hall is a large area consisting of a long hallway leading from the main gate, and a large open area with a staircase leading downwards to the Refinery, and another staircase leading to a second floor from where the Archives can be reached.
The area is in a partial ruin when the game takes place. Some pillars and a staircase have collapsed, there's a hole in the ceiling and some doors are mysteriously boarded up, most likely by Alexander's servants who were reinforcing weaker structures that the Shadow threatened to collapse.[1]
The Shadow covers the main entrance gate to the castle in its residue if the player interacts with the large door (yet again making an escape attempt impossible), as well as the path to the Refinery. The player will have to prepare a corrosive liquid in the Laboratory and use it to dissolve the organic matter to gain access to the Refinery. The solution has no effect on the Shadow's residue on the entrance gate.
From the Entrance Hall you can gain access to several other locations:
Refinery- Can only be accessed after getting rid of the residue.
The Shadow gradually consumes this area as Daniel makes progress. This starts to happen when he leaves the Archives after obtaining the Wine Cellar key, and then happens again after having gathered all the ingredients in the Wine Cellar and when the acid is finally created in the Laboratory. The cosmic force roars angrily and the corridors leading to these three areas are engulfed in its fleshy matter, making avoiding injury difficult.
This is also the very first place where the player encounters a flashback. It is triggered not long after entering the area and in it, Daniel and Alexander can be heard discussing the location of the Inner Sanctum.
An oil can be found in a chest in the corridor leading to the entrance door.
Another oil container can be found further down the corridor, closer to the door.
Trivia
The Entrance Hall seen from the main gate
When going up the stairs for the first time, Daniel will instinctively turn around as he hears a female voice crying "No! Get away from me!". The voice is identical to the voice of the girl who Daniel stabbed to death in the Storage. If Daniel decides not to go up the stairs, and enters the Laboratory instead and writes the memento for the needed chemicals, along with the chemistry pot, the same voice will be heard once Daniel re-enters the Entrance Hall.
When Daniel interacts with the entrance gate of the castle, he will lose some sanity as the fleshy residue the Shadow leaves behind appears. This is also the gate which Daniel leaves through in the "Revenge Ending".
Through the use of a glitch which abuses the games system for saving and loading, the Refinery can be reached without destroying the residue. This trick is used frequently by speedrunners. However if you are going to use this glitch, it is recommended that you enter the laboratory first and take the chemistry pot first, as you will be using it further in the game.
