The mystery revolves around the abbey library, situated in a fortified tower—the aedificium. This structure has three floors—the ground floor contains the kitchen and refectory, the first floor a scriptorium, and the top floor is occupied by the library.[5] The two lower floors are open to all, while only the librarian may enter the last. A catalogue of books is kept in the scriptorium, where manuscripts are read and copied. A monk who wishes to read a book would send a request to the librarian, who, if he thought the request justified, would bring it to the scriptorium. Finally, the library is in the form of a labyrinth, whose secret only the librarian and the assistant librarian know.[6]
The aedificium has four towers at the four cardinal points, and the top floor of each has seven rooms on the outside, surrounding a central room. There are another eight rooms on the outer walls, and sixteen rooms in the centre of the maze. Thus, the library has a total of fifty-six rooms.[7] Each room has a scroll containing a verse from the Book of Revelation. The first letter of the verse is the letter corresponding to that room.[8] The letters of adjacent rooms, read together, give the name of a region (e.g. Hibernia in the West tower), and those rooms contain books from that region. The geographical regions are:
The aedificium's labyrinth- Fons Adae, 'The earthly paradise' contains Bibles and commentaries, East Tower
- Acaia, Greece, Northeast
- Iudaea, Judea, East
- Aegyptus, Egypt, Southeast
- Leones, 'South' contains books from Africa, South Tower
- Yspania, Spain, Southwest outer
- Roma, Italy, Southwest inner
- Hibernia, Ireland, West Tower
- Gallia, France, Northwest
- Germania, Germany, North
- Anglia, England, North Tower
Two rooms have no lettering – the easternmost room, which has an altar, and the central room on the south tower, the so-called finis Africae, which contains the most heavily guarded books, and can only be entered through a secret door. The entrance to the library is in the central room of the east tower, which is connected to the scriptorium by a staircase.[9]
