The Wallabies open their tournament against Fiji on September 21 at the Sapporo Dome, a "spaceship-like" indoor venue that Cheika says must be seen to be believed.

The Wallabies coach spent Sunday afternoon there on a reconnaissance mission ahead of Saturday's third and and final Bledisloe Cup clash of the year against the All Blacks, to be played in Yokohama.

"I was really surprised by the venue," Cheika said.

"You see it from the outside but, when you're in there, you're going to realise that that opening game for us is going to be a really special occasion because there's not many games of rugby that are played in stadiums like that, or inside a venue like that, at all."

Used chiefly for baseball and soccer, The Dome opened in 2001 and was host to three games during the 2002 FIFA World Cup.

With Sapporo a gateway to some of Japan's premier ski slopes, The Dome also hosted the opening ceremonies to the 2007 Nordic World Ski Championships as well as being the first venue for both indoor and night-time skiing events at a world championship or Winter Olympic Games level.

"Even the way it changes from being a baseball stadium into a soccer or rugby pitch, it's going to be amazing to be honest," Cheika said.

"So it will be an experience for players and fans alike, like none other. After being there today, it really makes you look forward to that fixture.

"Well, as if you're not looking forward to it, but it really adds something different and it will make for an amazing atmosphere because the noise that will be inside that stadium will be outrageous.

"There ain't no opening of that roof. It's like a spaceship; it's closed in."

And that's not all.

"They've got a big glass panel at the back which blacks out all the light that goes in there so they can create that atmosphere," Cheika said.

"It has a (retractable) grass wicket that they roll in and spin around because it's an astro turf right now and they've got the actual pitch sitting outside. Directly outside.

"You can see it out there and it just comes in. Moves in on a sort of air bed, rolls into position, they spin it around and they set up a stadium around it.

"It's pretty outrageous."

Australian Associated Press