and 33 feet high. There are galleries at three levels above the floor. The feasibility of installing a mezzanine floor to make better use of the space has been considered on two occasions. The South Reading Room is used for consulting archives, manuscripts, maps and other printed materials. Carved above the entrance is the room's original name the Print and Maps Room. Above it on the second floor of the south wing is the Gregynog Gallery where temporary and permanent exhibitions display the treasures of the Library's collections. A six-storey bookstack, which was completed in 1931, was built to increase storage space for the rapidly expanding book collection. A second bookstack was officially opened in March 1982. In 1996, the Third Library Building was opened, doubling the storage capacity of the Library. The second phase of the building was built by T. Alun Evans (Aberystwyth) Ltd. A fire on 26 April 2013 destroyed a section of roofing in an office area of the building. Restoration was assisted by a government grant of £625,000. Wartime sanctuary During the Second World War, many of Britain's most valuable artworks and manuscripts were stored in the National Library of Wales, which provided the evacuated treasures with a refuge from enemy bombing raids. The architect Charles Holden was instructed to design a tunnel for this purpose in the outcrop of rock close to the main building, with the British Museum sharing in the costs that this incurred. The tunnel was heated and ventilated to ensure the preservation of vellum, papyri and paper during its use from 18 July 1940 until 23 May 1945. In addition to an extensive consignment from the British Museum, which weighed over one hundred tons, the Library received forty-six boxes of manuscript and printed books from Corpus Christi College, Cambridge and over a thousand pictures, eighty-two boxes of books and twenty members of staff from the National Gallery. The Library also received irreplaceable items from other prestigious institutions such as the Ashmolean Museum, Oxford, Dulwich College and the Royal Society. A number of distinguished scholars from the British Museum accompanied the collections to Aberystwyth. Their senior member of staff was Deputy Keeper of Printed Books, Victor Scholderer, who responded to a letter from the Director, Sir John Forsdyke, by insisting that he and his colleagues would continue to sleep in the Library so that the tunnel could be checked during the