The Image Mill runs until Aug. 24 on the Quebec City harbourfront. (Jacques Boissinot/Canadian Press)

The gritty, industrial Port of Quebec is the backdrop, its collection of towering grain silos, the stage; the curtain goes up shortly after darkness falls.

Every night, sights from Quebec City's 400-year past are projected onto a viewing surface that stretches 600 metres wide and rises 30 metres above the port's Louise Basin.

To celebrate the provincial capital's 400th anniversary, the 40-minute exhibition, designed by Robert Lepage, Quebec City's own international theatre giant, is beamed onto the side of the immense Bunge grain warehouse.

With a surface area the size of 25 IMAX screens, Lepage's visual and audio display — known as the Image Mill — has been called the world's largest projection show.

From illustrations of French explorer Samuel de Champlain establishing his early settlement, to photos from the dark days under former premier Maurice Duplessis, Lepage broadcasts major events from the city's history books.

Organizers say the free exhibition, which opened June 20 and runs until Aug. 24, has been regularly drawing near-capacity crowds of 5,000 to the harbourfront.

Hundreds more have gathered each night to watch from several vantage points at higher elevations in the city.

Three years ago, the city asked Lepage to help commemorate its 400th birthday.

"He immediately thought about this idea … projections on those large grain silos in the harbour," Image Mill producer Michel Bernatchez said.

"What Robert told them was rather simple as a starting point: 400 years, 40 minutes.....It would simply, ideally be about the city's identity."

The Image Mill uses 27 video projectors to produce images on 81 grain silos, is 600 metres long by 30 metres high, and projects millions of pixels onto Bunge grain warehouse's south and west facades. This frame depicts a portrait of Alys Roby, a famed Quebec singer from the 1940s. (Jacques Boissinot/Canadian Press)

For the project, Lepage, the first North American to direct a Shakespeare play at the Royal National Theatre in London, assembled a large team of historians, archive specialists and technicians.

Bernatchez said Lepage's group built a 17-metre-high model of the silos, set up video projectors and pulled up chairs for the lengthy image-selection process.

"That's what they did for months, literally watching thousands of images," he said.

The show's images, borrowed from museums, television stations and even the NHL, evolve from engravings that depict the early years, to paintings, photos, video and computer graphics.

More than 25 massive projectors, housed in towers along the waterfront, cast the show onto the side of the concrete building.

The soundtrack, an almost Pink Floyd-like presence, is pumped out across the harbour — and up the slopes to the Old City — by more than 300 carefully positioned speakers.

Standing in the right spot near the port, one can hear the audio come through in surround sound.

Some 50 subwoofers installed beneath the docks shake the boards during certain scenes, including one that features a rumbling train.

Production director Mario Brien, who manages 15 light and sound technicians during each show, said it was a challenge to adjust the acoustics of the large, open-air theatre.

The sound is sent two seconds before the projection so they converge on the front of the audience, about 600 metres away, he said.

Brien said after years of work, he couldn't wait for opening night.

"I'm feeling a kind of freedom now, because we were so involved, so busy with the project," he said. "Now everything is going fine and we are very happy about it.

"This building here in Quebec City is like a big wall, so now, with the projection, there's another life passing through [it]."

Previous record set by projection on pyramids, firm says

Bernatchez said the company that rented the projectors to Quebec City said the Image Mill is the world's largest projection show.

He said he's been told Lepage's creation has eclipsed the previous record, set by a 300-metre-wide projection on the Egyptian pyramids.

"We believe them," Bernatchez said. "We'll see if some Guinness record guy comes over."

He's been amazed by the attention span of the Image Mill crowds.

"The odd thing is contrary to a rock show, people don't show up with their six-packs of beer and all that," he said. "It's very quiet."

"People are extremely silent on the site. They listen very carefully. It reminds something like going to church."

Ed Slattery stood on a pier in intermittent rain to watch the Image Mill. The resident of Beauport, Que., said it was worth it.

"I think it was fantastic," he said. "I thought it was a good representation of the history of Quebec and Canada. I'm amazed that they could put an image on those round towers."