As sporting and cultural heritage sites go, it's rather dusty.
Seb Grieve grimaces and adds another small cloud of chalk to the 14-year-old white layers in the rafters above him, as he falls to the padded mats on the floor.
Which, if you're a climber, gives you some indication of the difficulty of the walls in The Schoolroom.
Since 1993 climbers from Sheffield, Scotland, the USA and Europe have hauled and twisted themselves up and down the carefully angled plywood boards built into an old classroom of the 19th century Heeley Bank Infants School.
"This is part of the country's climbing heritage," says Roy Mosley.
The Schoolroom was originally built by a group of Sheffield climbers who wanted a challenging training facility for the times they couldn't get out to the cliffs and edges of the Peak District.
"At the time this was the only one of its kind," says Seb. Other places around the world have copied it since but they're not as good, he adds.
The Schoolroom climbing walls are set at various angles between 12 and 50 degrees and are replete with tiny foot and hand holds designed to make the climbing 'problems' as difficult as possible.
A fabled guidebook records the new moves and routes carefully. "That's it over there," says Seb pointing to a grubby corner of the room. "So far there are about 300 routes."
These have innocuous names such as 'Chalk and Blow', 'Basic Bernie', 'Schoolgirl' and 'Pinky and Perky' and official climbing grades from 6A to 8B.
To the non-climber 8B may sound more like a sketching pencil than an extreme sports challenge but Roy Mosley puts the term into perspective.
"8B is world class," he says. "There are probably less than ten people in the world who could climb those. And two of them are from Sheffield."
To Roy, The Schoolroom is like the famous St Thomas' boxing gym of Brendan Ingle. "It's a grass roots facility for the hard core climbers of Sheffield. It's not glamorous, it's functional, but it sets the world standard."
Roy and Seb pick their way along the walls, dangling from inch-wide ledges or hanging upside down like spiders in khaki shorts.
On the wall is the word 'SHAFT'. "Same Hands As Feet Throughout," says Seb of one of The Schoolroom ground rules.
"You have to use the same holds with your feet as you use with your hands. It's to make it harder."
Roy and Seb list some of the world famous rock climbers who've trained at The Schoolroom: Ben Moon, Malcolm Smith, Jerry Moffatt (and of course, Seb Grieve) and more recently Richard Simpson, who went on to climb all the hardest routes in the world over the last year or two.
There are 30 elite climbers subscribed as Schoolroom members, with a waiting list, and all were shocked at the news that Sheffield council was planning to sell the Heeley Bank Centre, the 130-year-old listed building which is home to the Schoolroom climbers and a curious mixture of other users.
After it closed as a school a quarter of a century ago, the building was turned over to community groups of different kinds who leased spaces from the council.
So as well as the climbers there are a number of sculptors, artists and craftspeople, a local history group, a writers workshop, several educational courses, a crche and a long-standing youth group catering for 50 young people.
Walking through the old Victorian building, the climbers pass holes in the ceiling, leaking roofs, wall-sized paintings, moody photographs and a sculpture of an ear canal.
A petition was raised against the proposed sell off and after meetings with council officials – including deputy leader Councillor Steve Jones – the closure was shelved.
"The campaign was successful," says Seb, who was one of the leaders of the Save Heeley Bank Centre pressure group.
"We're pleased we're talking to the council and the situation is improving. Now if we can find an active management solution, it will be fine."
That is, an arrangement whereby the Heeley Bank Centre is properly maintained and promoted, so that more groups and local people can make use of the building and its facilities.
The original council idea, to reinvest some of the money raised from a potential sale into the Heeley area, was rejected by the 1,000 local people who signed the anti-closure petition because they valued the facilities already offered by the centre, says Seb. "They didn't see the point of a new set of flats."
He believes a solution to make the best of the existing centre for the local community will be found, as recommended by the recent Quirk report into the use of old council buildings, which was launched in Sheffield.
The initial campaign to stop the sell-off may have been successful but Roy is keen the campaigners remain vigilant until the future of the centre and The Schoolroom is clear.
"The top climbers of today started here. And with the young guys coming up, the people training here now will be the future top of the world."
The latest cloud of chalk dust settles and Seb and Roy plan their next move.