Ontario's largest Imax theatre is once again open for business.

The Cinesphere at Ontario Place will now be open on weekends year round. Eleanor McMahon, Ontario's Minister of Tourism, Culture and Sport, officially made the announcement Thursday night at a special VIP event, just before a screening of two Imax films: Dunkirk and North of Superior.

The revamped Cinesphere's new seats. (Susan Goodspeed/CBC)

"It's incredibly exciting to welcome people back to this iconic venue," McMahon said.

The Cinesphere still looks the same on the outside, but there have been some big changes inside.

"We've replaced the screen," McMahon said. "We've made upgrades to the entrance... the acoustics and the lighting."

There's also one big improvement in the projection booth in the form of a new laser projector. David Keighley with Imax said people will notice the difference in picture quality.

The Cinesphere has a new laser projector. (Susan Goodspeed/CBC)

"The pictures are actually breathtaking and more real," he said.

The Cinesphere was built back in 1971, and was the world's first permanent Imax theatre. It closed to the public back in 2012 along with the rest of Ontario Place.

"What we're looking to do now is reopen it and bring a whole new generation of people in here," said Ontario Place spokesperson Matt Ryan. "But also offer this theatre back to all the people who have this immense nostalgia of the great times that they had in here."

The rebirth of the Cinesphere is the second phase of a plan to bring Ontario Place back to life.

The first phase was the opening of Trillium Park and William G. Davis recreational trail last June. The province spent $30 million transforming one of the Ontario Place parking lots into a waterfront park.

Minister McMahon said the next phase will be to revamp the west island of Ontario Place, but officials are still not sure what to do with it.

Eleanor McMahon says the Cinesphere is the latest phase of a plan to bring Ontario Place back to life. (Susan Goodspeed/CBC)

"My ministry just closed a request for proposals process," she said. "And we had a number of really exciting proposals focused on innovation, design and creativity."

McMahon said the province wants Ontario Place to be a world-class venue, and the changes made on the west island will be the key to making that happen.

"We're trying to dream really big," McMahon said. "So if I think about an iconic cultural space, if I think about a cultural innovation space, if I think about something that brings people year round to Ontario Place."