(Corrects reference in lead to who has access to areas being opened up)
By Jonathan Allen
NEW YORK, Dec 19 (Reuters) - The New York Public Library released designs on Wednesday for an overhaul of its flagship Beaux-Arts building in Manhattan that will open to the public spaces that only lib rary staff hav e seen for the past few decades.
Under the plan, patrons will be able to borrow books from a new 100,000-square-foot lending library, creating what Mayor Michael Bloomberg said would be the largest combined research and circulating library in the world.
"With the Central Library Plan, we will open up more of our landmark building to the public, offering both circulating and research collections in one place, as well as the programs, classes, materials and services needed by our patrons," New York Public Library President Tony Marx said in a statement.
The building, with two stone lions famously guarding the entrance on Fifth Avenue, opened in 1911 and was declared a National Historic Landmark in 1965. It became a research-only library in 1981 when the lending library was rehoused in a relatively drab building across the street.
That building will be closed when the renovation project is completed in 2018.
Project architect Norman Foster, who has previously designed modern additions to other historic buildings such as the British Museum in London and the Reichstag in Berlin, said the flagship building's chandelier-bedecked Rose Main Reading Room would not be touched.
The library is making space for the lending library and increased research space by removing much of its stacks - seven stories of steel shelving containing millions of research volumes - at the rear of the building that are currently closed to the public.
Many scholars had previously criticized early plans to send most of the displaced volumes across the Hudson River to a storage building in New Jersey, saying the library's mission as a research center would be harmed if it were to take up to 24 hours for a requested book to arrive.
In response, the library said in September it had been given an $8 million donation allowing it to expand its underground storage space and keep onsite 3.3 million of the 4.5 million volumes currently stored there, with the remainder available nearly instantly in digital formats.
The library had earlier estimated the plan would cost $300 million but said on Wednesday the final budget would be higher, although it was not yet finalized. Bloomberg, who has endorsed the project, has said the city will contribute $150 million.
The library said the remainder of the funds will come from sales of buildings it owns nearby, and that consolidating several midtown libraries into one building will save about $15 million a year, which it will spend on librarians and books.
The plans still require approval from various city agencies, and the Landmarks Preservation Commission will have to give its approval for what the library calls "relatively minor" changes to the building's exterior before construction can begin next year. (Editing by Cynthia Johnston and Lisa Shumaker)