The first of the orange-clad rope workers jumped over the top of the Arc de Triomphe and started abseiling down the monument just as the sun rose over downtown Paris, unrolling a stretch of silvery blue cloth that shimmered in the early light.

As the first abseiler reached the top – 50 meters above the earth – someone applauded, but the majority of the spectators simply held their breath. It was a long and careful process that required them to stop every few meters to correct the folds in the cloth while avoiding touching the arch itself.

The enormous task of covering the Arc de Triomphe in 25,000 square meters of cloth and posthumously completing the artist Christo's 60-year ambition has started.

There was excitement, passion, and a few frazzled nerves as additional rolls of recyclable material arrived, along with more rope experts — a total of 95 – for an operation that blended art and engineering on a huge scale.

There was also sorrow that Christo and his French wife, Jeanne-Claude, who had originally envisioned L'Arc de Triomphe, Wrapped in 1962 while renting a tiny room nearby, were not there to witness it. Christo Vladimirov Javacheff, a Bulgarian-born artist, died in May of last year, while his wife and creative collaborator — the pair collaborated under the name Christo – died in 2009.

Christo provided minutely precise sketches and specifications covering every visual and artistic element of how he intended the wrapped arch to appear when he covered the Reichstag in Berlin.

“This is the vision of Christo and Jeanne-Claude. “It's critical that we pay attention to every detail that Christo requested,” said Vladimir Yavachev, the artist's nephew who is in charge of the wrap. “Christo designed it down to the smallest detail, and we have to stick to it.” It indicates we did a good job if people remark it looks exactly like the drawings.”

Engineers and construction crews have been preparing the Arc de Triomphe around the clock since July, constructing scaffolding to keep the fabric away from the monument stone. The actual wrapping should be completed by Monday evening, at which point the cloth will have been fastened with red cords.

Christo created a photomontage of how he imagined the wrapped arch would appear in the 1960s, but he never presented it since he assumed they would never get the required permits. The concept was resurrected in 2017 to coincide with a Christo show, and it was authorized by the Paris municipal government and the Centre des Monuments Nationaux, which supervises public monuments.

Christo's preliminary studies, sketches, and collages of the project, as well as scale models, works from the 1950s and 1960s, and original lithographs on various themes, have all been sold to finance the €14 million (£12 million) project. It has never gotten any support from the government.

Following the installation of the material and cables, a meticulous procedure of inspecting the work of art and ensuring that the final wrap appears precisely as Christo imagined it in his designs will begin.

L'Arc de Triomphe, Wrapped will open on September 18th and, like previous Christo creations, will be a temporary installation. On the 3rd of October, work on removing the covering will begin in preparation for Armistice Day celebrations. Officials from the Paris monuments office have supervised the whole installation to ensure that no blemishes remain on the arch.

Christo studied in Sofia before fleeing to the west in 1957, stowing away on a train from Prague to Vienna, then on to Paris via Geneva, where he met Jeanne-Claude Denat de Guillebon. The couple arrived in New York in 1964 and lived there illegally for the first three years.

The wrapping of the Pont Neuf in Paris in 1985 is one of Christo's most well-known works.

“I started working with Christo when I was 17 years old – you could call it underage labor,” Yavachev said. For the last four years, I've been working on this project.

“Right now, we're concentrating on getting the job done, and we'll deal with our emotions later. It's a kind of treatment in which you focus on something in order to avoid thinking about something else. The fact that Christo isn't here is the greatest difficulty for me. I miss his passion, criticism, and energy, and that is the most difficult task for me.”

“One very important thing is that people can walk around the Arc de Triomphe and touch the material,” he said. It's a living piece of art that moves with the wind.”

“Christo and Jeanne-Claude believed their work was ultimately about freedom,” he said when asked what it all meant. This piece of art could not be owned by anybody, not even them. Everyone may have their own interpretation, and each interpretation was significant and correct.”

Christo stated in an interview soon before his death that the Arc de Triomphe project took 18 months to plan, compared to 25 years for the Reichstag and 26 years for The Gates in Central Park.

He said that he had been asked to perform "something" outside the Pompidou Centre to coincide with his show, but that he had declined, telling the institution, "I will never do anything here." If I do anything, it will be to cover the Arc de Triomphe; otherwise, nothing.”

“The Arc de Triomphe packaging is quite unique,” he remarked. “It all came together in a flash. Of fact, the idea dates back to 1962, but the approval came out of nowhere.

“In the 1960s, I created a number of plans that we sold to raise funds for other projects. I also created a very complex collage version with fabric towards the end of the 1980s, when we believed the Arc de Triomphe project would never see the light of day. To be honest, it's weird how everything came together so quickly.”

“I never thought it would happen...,” he said. However, I want you to know that many of these initiatives can be completed without my participation. Everything has been written already.”

“We're very proud to be a member of the team to finish Christo's dream,” Mike Schlaich, of the German engineering firm SBP, told media. It's a beautiful item, a beautiful work of art. It's precisely as Christo envisioned it. We engineers had to learn the artists' language.”

“The particular challenge with any Christo project is that it's always a first time; it's never been done before and it will never be done again,” said Vince Davenport, one of Christo's engineering consultants who worked with him for 35 years.

“It's very emotional,” he continued, his voice trembling. We only wish Christo could be here to see it.”

Thanks to Kim Willsher at The Guardian whose reporting provided the original basis for this story.