Yesterday were celebrated its 300 years of age.
.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 36,000 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).
The library is known for homing bats which protect the books from silverfish.
The Library was used in Gulliver's Travels (1996) as the Great Chamber of War for the Emperor of Lilliput. Wikipedia