Beneath the Chamber of Secrets of Ravenclaw Temple, inside the newly completed temple library.
The library had been placed inside an independent space rather like the Room of Requirement. It seemed to be formed from an indeterminate, infinite number of equilateral triangular rooms joined together. At the center of the rooms on each level was a hollow shaft with no ceiling or floor, used as a ventilation duct and ringed by low railings. Looking out from any railing, one could see it stretching upward to a distant height and downward into an endless abyss, yet every level divided above and below without end could be seen, each one partitioned into library rooms with exactly the same layout.
The lighting was handled by crystal balls made to resemble stars and celestial bodies, suspended in the rooms. These celestial crystal balls were named after the heavenly bodies that lit the sky, and they moved slowly through each triangular room along fixed trajectories. The light they gave off was continuous but did not sting the eyes; every glow was just right and comfortable, and could even be adjusted to a certain degree according to a reader's needs. In fact, this magical creation Arthur had devised after taking inspiration from Muggle smart lighting had already become widespread in the Floating City. Within the range of the Energy Core, the difficulty of making and using them was almost negligible compared with traditional old methods.
In each triangular room, every wall was filled with bookshelves, and in the center of each wall was a doorway. Going out through any one of those exits led to the next triangular room. Every level had infinite triangular rooms, and these triangular rooms were arranged like a honeycomb.
Almost every vertical surface of every triangular book room was covered with