But this isn't ordinary wear and tear caused by 80 years of visitors walking to and fro laden with books – instead, it is a sign of bomb damage caused when nearby Fitzalan Square took a direct hit during the terrifying Blitz raids in 1945 at the height of the Second World War.
However, as shaken as the place was, it remained standing and is still the heart of the city's library service today, as well as housing the important Graves Art Gallery.
"This building means a lot to people in Sheffield," says researcher Val Hewson, as she recalls more recent turmoil when the Grade II-listed premises were nearly leased to overseas investors who wanted to create a five-star hotel.
"There was lots of protest. I'd love it to be refurbished and brought up to date - Sheffield needs that sort of library."
People will look behind the scenes at the Surrey Street venue, examine its architectural features and discover more about its history on free tours happening this Friday as part of the annual Heritage Open Days festival. Val, meanwhile, is giving a separate talk next Tuesday about former chief librarian Joseph Lamb - hailed as a 'driving force' who put Sheffield on the map in the mid-20th century for the standard of its lending facilities.
"I've always been slightly cracked about libraries," says retired civil servant Val, who is studying popular reading as an honorary visiting fellow at Hallam University. Born in Gateshead, she signed up to borrow books in Sheffield as soon as she moved to South Yorkshire more than 30 years ago, reflecting that she has ‘been a member of a public library for 59 years’.
The Central Library, Val says, is 'very grand' - and would have been part of something even more impressive had early plans come to fruition.
"It's part Art Deco, and part something called Beaux-Arts," she explains, pointing out a carving of the mythical 'figure of knowledge' on the most prominent corner facing the Winter Garden.
"Great architects worry about why it's on such a narrow street. But the idea, in the 1920s, was that it would be one side of a great civic square, with a college and law courts and town hall offices. Of course, the other three sides were never built."
There was a predecessor on the same site - but it wasn't originally intended as a library, despite the Victorian zeal for promoting reading as a way for the working classes to better themselves. The Sheffield Mechanics' Institute and an old music hall next door were used until it became clear that a proper solution was needed.
"The books were all out of date, and they talk about there being dust inches thick on top of the shelves," says Val. "Most of the lights didn't work and the buildings weren't safe, so no-one wanted to come."
Contemporary reports describe this period as the 'years of stagnation'. "Borrowing had gone down and there had been no new library built in the city since 1906. Things were in a bad way."
The head librarian was 'let go' by the council and Richard Gordon was brought in as a replacement. Lamb was picked as Gordon's deputy, then rose to the top job in 1927 when his boss left for Leeds.
Research trips to America were taken to seek out ideas for a new Central Library before proposals were drawn up. The total cost of construction came to £141,700 - roughly £7 million today - including a £30,000 donation from benefactor J G Graves.
"He gave the council the money to finish it on the condition they put the gallery on the top floor, which Lamb didn't really want," says Val. "But he was a pragmatist so he said 'Yeah, fine'."
The Queen Mother - then the Duchess of York - led the official opening in 1934.
"It was state of the art," says Val. "It had all the latest equipment, a children's library, a science and technology library - as befits Sheffield - and a reference library. It had reading rooms, and the theatre in the basement which was used for lectures, films, and plays... and still is."
Inside, many of the original custom-designed wooden fittings in oak and walnut remain, while the front of the building is made from Portland stone. Around the entrance door there are nine carvings symbolising literature, music, drama, architecture, sculpture, painting, maths, chemistry and astronomy.
Lamb drove up the number of borrowings from 700,000 in 1920 to over four million by 1950, stepping down seven years later. Among his innovations was the Sheffield Interchange Organisation, an information-sharing scheme aimed at manufacturing businesses.
"He was quite a complex man," Val says. "But he had a real vision and he was driven to achieve. Frankly, I'd like to see a room named after him or at least a memorial. He deserves it. He's as important a person as Graves. He came from a working-class family, didn't have much education and his father died early, so he went into the library because that was a good, secure white-collar job."
She accepts the Central Library has a 'shabbiness' about it these days. In 2017 the council announced its intention to create a £20 million replacement on a new site, turning the existing premises into a 'cultural hub' alongside Museums Sheffield, but little has been heard of this scheme since.
"It's old now," says Val. "But it still works, so it shows how well it was designed and built originally, and how it still meets people's needs."
Many of Sheffield’s branch libraries – but not the Central Library – are now volunteer-run following cuts in 2014.
Libraries, Val thinks, are 'underrated and under-funded'. "I understand why. Councils face really difficult challenges, and I don't envy them. In lots of ways, libraries are an easy cut to make, but I think it's very short-sighted. Libraries belong to nobody and everybody - they're a really important space for the community. You can't rely on Google."
Tours are on Friday, September 13, at 11am and 2pm. Places are limited. The talk - Joseph Lamb and the Making of Sheffield Libraries - is at 10.30am next Tuesday, September 17. See www.eventbrite.co.uk to book. Heritage Open Days run from September 13 to 22 with more than 130 events in Sheffield. See www.heritageopendays.org.uk for details.