Clambering up a rusty ladder, pigeons flapping around his ears, Karl Travis is about to see Sheffield as only a handful of people have witnessed the city.
Having carefully made his way past the peeling paintwork, exposed rafters and smashed glass within the crumbling Old Town Hall, he is ascending the building's famous clock tower.
The 31-year-old, of Hunters Bar, is one of a growing band of 'urban explorers' investigating abandoned buildings in Sheffield and across the UK and chronicling the eerily beautiful scenes of dilapidation they find within.
Mr Travis is a relatively new convert to this growing craze, for which Sheffield, with its many festering factories gradually being reclaimed by nature, has become somewhat of a mecca for enthusiasts.
But in the last year, since being bitten by the bug, he has seen inside the rotting husks of edifices ranging from empty hotels and derelict churches to a deserted asylum and a once-opulent mansion left to fall into ruin.
He shares his adventures on Instagram and YouTube, where his channel has more than 2,000 subscribers and some videos have been viewed more than 10,000 times.
The father-of-three, who works as an industrial cleaner, says he has always been a bit of a history buff and enjoys getting a unique perspective on the city's past, bringing him closer to experiencing life as former inhabitants did than he would be walking around a listed building preserved in aspic as a visitor attraction.
Part of the appeal is seeing these buildings in a way few others will, but he also gets a kick out of recording the gradual deterioration of these buildings, whose fading grandeur he finds beguiling.
"It's a fantastic hobby. There are so many amazing places out there which people don't get to see on a daily basis, and I love sharing what we see so others who might not otherwise be able to can appreciate it," he says.
"I've always had a curiosity and as a 10-year-old I remember being fascinated by an old miners' welfare office I found in Stocksbridge, where I grew up.
"I see the beauty in decay and I like showing people what's happening to these buildings because sometimes it makes them think 'wow, that's really gone downhill in the last 10 years'."
The law surrounding urban exploration is something of a grey area and many enthusiasts' sites advise participants to seek the owner's permission where possible or advise police before entering a building.
Mr Travis accepts that entering premises without the owner's permission amounts to trespass but he says this is a civil offence rather than a criminal one and he has never been prosecuted or even contacted by any landowner.
He says he never breaks and enters, as this is a criminal offence, only ever gaining access through open windows and doors or gaps in the roof or walls, even if this means shimmying up a drainpipe to get in.
He also claims to be scrupulous about leaving premises exactly as he found them and never stealing even the smallest souvenir, vandalising the property or causing even accidental damage.
Last March, a student fell to his death inside the old Hallam Tower hotel in Broomhill, where an inquest last month heard how there had been an 'epidemic' of trespassing.
Mr Travis had filmed inside the building just weeks before the tragedy, which prompted a plea from the owners for urban explorers to stay away for their own safety, and he wept when he learned of the teenager's death.
"I always say in my videos that these places can be dangerous and people need to be aware of that. Safety is paramount," he said.
Neither he nor any friends who share his passion have ever been seriously injured, he says, though he did once put his foot through a missing stair board at the Old Town Hall and says the pain was 'horrendous'.
He would explore solo at first but now always goes accompanied so there is someone to help should something go wrong.
"Some of the places we explore are deadly dangerous. I've been in buildings with six foot pieces of glass hanging from the ceiling, which would kill you if they fell, and I've walked across beams 200 feet in the air."
"But I like living on the edge and you don't always appreciate the danger until afterwards, when the adrenaline subsides."
Mr Travis says his mum always worries and asks him to call to let her know he's home safely.
But despite the dangers, he says he would not be averse to his children taking up the hobby when they are older, provided they do so safely and responsibly.
He has already accompanied his eldest son, aged 12, on a visit to what he describes as a 'very safe' site with no climbs.
Finding new locations can involve painstaking research and Mr Travis likes also spends time swotting up on the history of those places he explores so he can fill viewers in when posting his videos.
He only shares the locations of already well-known sites, he says, to prevent more hidden ones falling prey to thieves and vandals.
He claims to have visited around 90 per cent of Sheffield's abandoned places and has travelled further afield to cities including Leeds, Manchester and London.
The urban exploration community is a generally friendly one, he says, and he has made numerous friends through his hobby, as well as his girlfriend Kelly Tatler, aged 29, from Derbyshire.
But it can be a competitive environment, he adds, with enthusiasts trying to outdo each other at finding new places and producing the best videos and photos.
Having started out armed only with a mobile phone and a camera, Mr Travis soon invested in more hi-tech equipment like a GoPro video recorder and a DSLR camera.
His videos come with a running commentary as he reacts to his discoveries with comments like 'it's just surreal', 'it's proper creepy' and 'I've heard a few stories about people seeing ghosts down here'.
Not everyone is a fan of urban exploration, with property owners in particular taking a dim view of the pursuit.
One developer, whose property has become a magnet for enthusiasts but who asked not to be identified, said: "It's trespass because developers are responsible for what happens on their site.
"It's not safe for people to be wandering around inside sites like this and we don't want anyone to get hurt so we would urge them not to do so."
For campaigners fighting to save dilapidated buildings, however, urban explorers can perform a useful function in documenting those premises' decay.
Valerie Bayliss, of the Friends of the Old Town Hall, said: "There's a big line to be drawn between vandals and urban explorers, who leave the place as they find it.
"We never condone trespass but over the years the urban explorers who've been into the Old Town Hall and shared photographs have provided a continuing record of the deterioration, which is helpful to have.
"We're very aware of the dangers within the building, however, and we're certainly not in the business of encouraging people to go inside."