Region
Library map
What sits in the library
Named sub-areas are the Rhetoric Shelves and the Exhibition Room, each with a Mirror of Life. Carmilla, The Occultist, is in the Observatory at 4,500 health. She drops The Occultist card. Lich's Mark and Midnight Tear are both placed on the Rhetoric Shelves.
The planetarium puzzle uses three orreries: a man, a woman, and a skull. Durandal is in Lisa's Laboratory and requires Aerial Rush, reached from the Curiosity Cabinet by bouncing across four light orbs. The exact door from the Main Hall into the library is not written up as a turn list, so I am not inventing one.
Why this page is not the puzzle solution
The planetarium steps and the Durandal jump are long enough to be their own pages. This map tells you the rooms exist and which fight is in the Observatory. Follow the links for the orb order and the sword route.
What I ran into
I kept getting lost between 'where is the library' and 'how do the orbs work'. They are different questions. This page only answers the first, and it admits the connecting corridor from the Main Hall is not documented turn by turn.
Questions
Where is Carmilla?
The Observatory in the Library.
Where is the planetarium?
Inside the Library. The solution page covers the man, woman, and skull orreries.