“Human Spider” Alain Robert has been arrested after he climbed the 754ft (230m) Heron Tower in the City of London.
The 56-year-old Frenchman, with no safety gear or rope and using his bare hands, took about 50 minutes to reach the top in the illegal ascent.
It was a “medium” climb, he said – not “easy”, but not “ridiculous” either.
The daredevil was detained for causing a public nuisance.
Mr Robert, whose previous death-defying climbs include the world’s tallest building, the Burj Khalifa in Dubai, and the Empire State Building in New York, said before setting off that he was likely to be arrested following the feat.
“I’m not crazy,” he told Sky News. “What I’m doing may seem crazy but I’m not that crazy.”
Mr Robert, who is a grandfather, uses chalk to improve the friction between his skin and the building but also tapes his fingers and wears wafer-thin gloves.
His twin targets when he climbs a building are “going to the top”, and to “stay alive”.
He explained that climbing a tall building focuses the mind. “If you are shaving, or if you are cooking, you can also think about many other things,” he said.
“But when you are climbing, as I’m not using any safety devices, when life is at stake, I guarantee that you are focused.”
You are not thinking about “bills you haven’t paid”, he added.
Mr Robert is 5ft 5in and weighs about 7st 12lb (50kg), with a low fat ratio of bones to muscle which helps his extreme
athleticism and skill.
His last London climb was Portland Tower in 2007 and he said he only thought of climbing the Heron Tower after seeing some pictures of it two days ago.
Before that he had considered scaling the “Walkie-Talkie” tower in Fenchurch Street, or the “Cheesegrater” in Leadenhall Street.
The Heron Tower, on Bishopsgate, seemed “doable”, he said prior to setting off.
He wanted to make sure he was “not putting my life at risk”.
He had already “tried it a bit” after going along early in the morning, but lots of CCTV makes preparing for a climb “much more complicated than in the past”.
Asked if he ever gets scared, he said that, mostly, he “shouldn’t be surprised by the building”, following his experiences around the world.
He considers his biggest achievement to be climbing the Burj Khalifa, because “829m (2719ft) is quite something”, he said, adding: “It’s like really a gigantic mountain made by the human being.”
He also enjoyed climbing the Willis Tower in Chicago which is “nearly half a kilometre vertical”.
After he was arrested on Thursday, Commander Karen Baxter, from City Of London Police, said: “The incident has had a considerable impact on police, other emergency services and the local community.
“Our officers, the London Fire Brigade and the London Ambulance Service all attended this incident, taking them away from genuine emergencies.