This claim is based on its spatial dimensions rather than the collection of books it houses, which numbers around 60,000 volumes. The hall spans 70 meters in length, 14 meters in width, and rises to over eleven meters high at the crown of its vaulted ceiling (over twelve meters high in the central area). Forty-eight windows provide ample natural light, with an additional twelve windows hidden behind the bookcases. It is this light that imbues this majestic space, with its impressive scale, as a hall of openness, enlightenment, and liberal spirit. Besides light, it is the colors that give the room its incomparable appearance: the white of the shelves, the gold in decorations and ornaments, and the bronze-colored sculptures and carvings – a masterpiece of the Late Baroque period, designed by the architect Joseph Hueber.

The shell of the room was completed around 1776; the most important artists involved were Bartolomeo Altomonte (ceiling frescoes) and Joseph Stammel (wooden sculptures). The arrangement of the books in the large library room still corresponds to the well thought-out organisation concept that was developed when the room was completed. The collection was divided into subject groups, which can still be recognised today by the Latin inscriptions on the cartouches on the large bookcases.