The Rococo library, situated at the back of the second floor, is truly the highlight of this palace, rivalling the grandeur of the library of the Melk Abbey in Austria. Built by Manuel Caetano de Sousa, this library is 88 m long, 9.5 m wide and 13 m high. The magnificent floor is covered with tiles of rose, grey and white marble. The wooden bookshelves in Rococo style are situated on the sidewalls in two rows, separated by a balcony with a wooden railing. They contain over 35,000 leather-bound volumes, attesting of the extent of western knowledge from the 14th to the 19th century. Among them, are many valuable bibliographical jewels, such as incunabula. These beautiful finished volumes were bound in the local workshop (Livraria) in the rocaille style (also by Manuel Caetano de Sousa).
Besides natural techniques of conservation for the books, such as the lack of space between the wall and the book (so it doesn’t createhumidity), there are also a few bats that inhabit this library eating any insect that could destroy this invaluable treasure. The bats are kept in boxes that are placed under the bookshelves. At night, the boxes are opened and the bats feed themselves 500 insects, equivalent to the double of their weight.
The Library was used in Gulliver’s Travels (1996) as the Great Chamber of War for the Emperor of Lilliput.
There are several legends regarding the palace. The most popular claims that giant rats, capable of eating people, inhabit the palace and leave it at night in order to kill what they can — cats, dogs, and people. The origin of this legend is the large sewer system built below the palace. Another legend speaks about the existence of a secret tunnel, linking Mafra to Ericeira, and that King Manuel II used the tunnel to escape exile and remain in Portugal.