The castle is presumed to have been built in the middle ages. Brennenburg Castle was rebuilt centuries before the game takes place by Alexander of Brennenburg in the late 16th century, after it was consumed by a fire. After Alexander rebuilt it, he made it his home. The castle is located deep in the woods of eastern Prussia (most likely in today's northeastern Poland or Königsberg), near the town of Altstadt. For the locals, Brennenburg Castle was a place to fear, as villagers sometimes disappeared, presumably kidnapped and taken to the castle for unknown purposes.
Amnesia: The Dark Descent
The castle's history is again shrouded in mist up until the 19th century, when the events of Amnesia: The Dark Descent took place. With Daniel 's arrival and Alexander's acquisition of an intact orb his centuries long plan to return home is put in motion. As the events progress the castle is continuously assaulted by the Shadow. Large portions of the castle which hasn't been tended for centuries begin to collapse as the Shadow consumes more and more infrastructure in pursuit of Daniel. Finally after the confrontation in the Inner Sanctum the castle appears to have partially or mostly collapsed.
After the events of The Dark Descent
It is unknown what became of the castle in the next few decades. However the experiments of Oswald Mandus, which are based on those from Brennenburg might imply that the castle was not entirely forgotten and that the ruins were excavated and explored. It is also implied that Oswald had a body of a Gatherer sent to him, which was most likely found in the remains of Brennenburg.
The castle is built of large flag stones and has many stone columns. As expected of the time period, it is lit by candles and decorated with paintings and tapestries though, as mentioned before, the castle's wards have fallen into a state of decay and ruin. When the immense Shadow arrives, it causes parts of the castle to collapse entirely forcing the baron's servants to reinforce weaker structures. While this means that many of the wooden structures are crumbling, much of the stone that makes up the walls and ceilings seems to remain intact, specifically in the back rooms as Daniel draws closer to Alexander.
On the other hand the exterior appearance of the castle is unknown. The only instance when the outside is glimpsed is in the Study, when the player jumps outside from window to window. There is also a concept art depicting the castle as having numerous, large towers and walls. The castle is perched atop a forested mountain with Altstadt below.
Brennenburg Castle is a large, almost labyrinthine and rotten compound. At the time of The Dark Descent, many areas of the castle have begun to fall into ruin.
- Rainy Hall (S)
- Old Archives (S)
- Entrance Hall (H) (S)
- Refinery (LR)
- Cellar Archives (HR)
- Archive Tunnels (HR)
- Back Hall (H) (S)
- Prison (HR)
- Cistern Entrance (H) (S)
- Sewer (HR)
- Nave (H) (S)
- Inner Sanctum (LR)
- Orb Chamber (S)
(S) Denotes the area is mostly Safe. No encounters with any kind of monsters will occur in these areas.
(LR) Denotes the area is of Low Risk. Non-hallucinatic encounters with monsters may occur in these areas.
(HR) Denotes the area is of High Risk. Encounters with different kinds of monsters will occur in these areas.
(H) Denotes the area is a Hub. A hub is a large, safe area with doors leading to several other rooms you will have to traverse to to reach your goal.
For the first part of the game, you will not run into any monsters, as the Old Archives and the Main Hall serve as a tutorial of sorts to familiarize the player with the controls. However, in the Archives and Wine Cellar, you have the possibility of seeing your first Servant Grunt without actually having to risk being ripped apart, as it is walking away from you and is not scripted to attack regardless of your actions. An audible sound of a Servant Brute can be heard in these areas which cannot be seen, only heard. The first dangerous encounter of a Servant Grunt occurs in the Refinery, and once you escape the water lurkers (Kaernks) in the Cellar Archives, you should prepare for a myriad of encounters in the Storage and the Prison Blocks. The Servant Brute is visible in both blocks of the Prison, but is not a threat until you reach the Sewer, and becomes a higher threat in the Morgue.
There will also be a Grunt appearance in the Guest Room, before or after you go to the Storage (depends on your actions). However, it's not a forced encounter with the Grunt in the Guest Room, you can choose not to go to the right (after you enter the closet room), then the monster won't appear at all. You have to get the key for the Machine Room in the closet room.
- The Castle is said to be located deep in the woods of Eastern Prussia near Königsberg, as the name was mentioned in one of the Notes found in the game.
- The Castle's interior bears a strong resemblance to the castles built by Teutonic Knights in early medieval times. Brennenburg may be inspired by Malbork Castle, a fortress of the Order of Teutonic Knights, which is called Marienburg in German.
- The location of the castle Brennenburg might have been inspired by Brandenburg; A German state located in the north-eastern part of the country. Another reason that might support this is Order of the Black Eagle; An organization Alexander is a member of was founded on January 17, 1701 by Elector Friedrich III of Brandenburg who later became Frederick I of Prussia.
- "Branden" is the German word for "surge", while "Brand" means "fire." The word "Brennen" can be translated to "burn" or "firing". Although the word "Schloss" is more common, "Burg" can also mean "castle" in German, making the use of "castle" after the name redundant. Therefore, "Brennenburg" can be roughly translated to "Burning Castle", which makes sense since the castle, considering its history, was in fact rebuilt after a fire had caused the castle to burn down to the ground.
- The village nearby, Altstadt, translates to 'old city' and is a term used to describe the historical part of a city.
- Nave, Choir, Transept and Chancel are all terms used to describe various sections of a traditional Cathedral. This might or might not be a reference to the medieval era inquisition made by the Roman Catholic Church, as there are torture devices found in these sections which were used by the church to punish the criminals.
- In the Revenge Ending, the fate of Brennenburg Castle, while not directly shown, is audibly heard falling apart as the entire structure collapses — once Daniel has left safely.
- As Daniel flees he does not encounter any Grunts, Brutes or otherworldly monsters, the entire place is deserted. Alexander's servants and the Kaernk most probably died after direct contact with the Shadow passing through or cave-ins.
- It is unknown how Daniel managed to escape the castle as some parts of the way were either blocked or crumbled, especially the elevator section, but it can be assumed that there was another way to get back to the surface. Either Daniel found the way out by himself or the Shadow provided him a hidden path to escape is unknown.
- It appears that Oswald Mandus is well aware of the castle's existence and location as he was able to procure a body of a gatherer to use as template for his manpigs.
- In a deleted note in Amnesia: A Machine for Pigs, Oswald Mandus states that local peasants set fire to the castle some time after the first game, badly damaging it. However, Oswald was able to recover Alexander's travel journals, which inspired his own hunt for Orbs in the America. 
- In most hub areas, the inscriptions denoting the purpose of the rooms beyond are in Latin. Examples of this are the cella vinaria for the Wine Cellar and the fabrica eliquatoria for the Refinery. In addition, many areas have their sub-spaces divided by Latin terminology, such as the instrumenta for the equipment room in Storage, or the Historia Loci and Libri Rari for specific rooms in the Archives.
|The Dark Descent locations|
|Main campaign||Brennenburg Castle locations||Rainy Hall • Old Archives • Entrance Hall • Archives • Wine Cellar • Laboratory • Refinery • Cellar Archives • Archive Tunnels • Back Hall • Storage • Guest Room • Study • Machine Room • Elevator • Prison: Southern Block • Prison: Northern Block • Cistern Entrance • Control Room • Cistern • Morgue • Sewer • Nave • Chancel • Transept • Choir Entrance • Choir - Main Hall • Cells • Inner Sanctum • Orb Chamber|
|Other locations||London • Algeria • Altstadt • Tomb of Tin Hinan • Zimmermann Farm|
|Justine campaign||Cabinet of Perturbation||Cells • Library • Dungeon • Crypt|
|Other locations||Florbelle Estate|