This is part of the quest Public Knowledge. The area is filled with supermutants and the library defense turrets and protectrons.
Street entrance has advance lock. The alternate entrance, Copley Station beneath the library has the same difficulty as well.
From the main entrance, there’s a book return terminal near the door. It has a Massaschusetts Surgical Journal magazine that you can get by trading 50 book return tokens. The library has several overdue books you can surrender for 5 tokens each.
In the northwestern hall, there’s a terminal behind the pile of shelves and desks to get the Library Storage Key and bobby pin boxes. Open the door behind it to get the Intelligence Bobblehead sitting on the control panels of the machine. Use the Library Storage Key on the white door behind the Curator’s corpse to find a steamer trunk, stealth boy, and other lootable containers.
The filing room in the far eastern wing has a chem station and cabinets with components. NE corridor leads to the stairs leading to the lower portion of the library. The hall connecting the room with the stairs and the western wing has a chained door. Unchain it and open it if you want. There’s also a novice terminal in that room which you can use to deactivate the turrets and protectrons. The grand stairs Lead to the Copley Station.
Copley Station