Interesting post about Amnesia!

[Prelauncher]

I searched the .lang file and found nothing about either Berlin nor Brandenburg, unless it was mentioned during a flashback you're just remembering it wrong.

However I found this:

Spoiler below!

<Entry Name="Note_CH01L03_VillageTales_Name">Local Folklore</Entry>
<Entry Name="Note_CH01L03_VillageTales_Text">Altstadt and Brennenburg Castle 1801
Another region rich with lore is Altstadt, deep within the East Prussian woods. For centuries there have been stories surrounding the hamlet and its neighbor, castle Brennenburg. The quiet forest-clad mountains dressed with scattered lakes is as picturesque as can be, albeit the area is haunted by the dark. Ask any local and you will hear proof of the widespread superstition. All travelers should indulge themselves in such conversations since it will certainly serve as exciting entertainment. All of them have their own twists on the tales, but there are some motifs that keep reappearing.(...)

EDIT Also I found this: "I looked up Brennenburg and traced it to the Prussian woods near the Baltic Sea"