In one of the most ambitious Christ Church Cathedral concepts yet, Bob Parker is calling for the historical ruins to be encased in a "crystalline structure" to serve as a reminder to the past.

The Christchurch Mayor has waded into the heated debate over the fate of the cathedral, but he comes armed with a bold vision.

He has suggested retaining as much of the cathedral's walls as possible, restoring the grand organ and pews, removing the cracked and weathered roof to expose the rafters and beams, and building a glass case over the ruins to open the building up to the stars.

The crystalline cloak would shield the cathedral from the elements but still allow church-goers to worship and visitors to wander through the remains of the original building.

His plan has been pitched to Anglican leaders but was yet to receive a price tag.

Parker envisaged stained glass windows suspended mid-air by wire, a glass structure being lit up from the inside at night and a rebuilt spire shooting out of the encasement to become the tallest point in the city.

The mayor said he found his inspiration from Norway's Hedmark Museum, which has a huge glass encasement protecting the ruins of the Hamar Cathedral.

Parker said he had been chewing the idea over for about six months and wanted to unveil it publicly to get feedback from the community and generate discussion about the possibility.

So far, he had raised his plan with a number of people, including Bishop Victoria Matthews who "positively received" it, he said.

The argument over the future of Christchurch's broken cathedral has polarised the community and wound up in a High Court battle, leaving the beloved building exposed to the elements for nearly two years.

Parker believed it was time to wind up the fight.

"I don't believe we should ever reconstruct and build the thing as it was. We should try to retain as much of the old, but not cover up what has happened here by rebuilding it to new," he said.

Within three generations, memories of the February 2011 earthquake would be scarce and Parker suggested the city "send a message to the future".

"We cannot ever completely forget what happened here, nor should we. We need something to tell that story, we need to retain one structure that is a record of what took place and I think the cathedral should be that project," he said.

Parker believed his vision could transform the wounded building into an "extraordinary tourist attraction".

DONNITHORNE UNVEILS PLAN FOR CHURCH

Architect Don Donnithorne has unveiled his vision for Christ Church Cathedral in a bid to drum up enthusiasm for repairing the forlorn building.

Donnithorne is shocked at Cantabrians' "negative attitude" towards the cathedral.

"Time has moved on and the enthusiasm towards the cathedral has disappeared," he said.

The fate of the earthquake-damaged building has been a contentious issue, with many wanting it torn down and replaced, while others are fighting to have it restored.

Demolition began last year, but in November a High Court ruling ordered that work be stopped until further notice.

Donnithorne said repairing the cathedral made more sense than the "enormous disaster" of the cardboard cathedral, a temporary replacement being built near Latimer Square.

The remaining structure of Christ Church Cathedral was sound and could easily be strengthened, he said.

"I see this as a challenge which can be met.

"When you look at the ridge of the roof it is as sharp and true as it can be," Donnithorne said.

"The view of the cathedral from the south side, as you approach from Colombo St, is in perfect shape."

Donnithorne released concept designs for repairing the cathedral in April, but his tower drew unfavourable comparisons with the fairytale Rapunzel's Tower.

He envisaged a new tower, complete with "massive concrete pillars" that would strengthen the cathedral by linking the west end to the existing structure.

It would be to scale with the tower that collapsed in the February 2011 earthquake.

"This is a most dramatic occasion for restoration," he said.

"It could be one of the finest cathedrals in the world.

"I am determined to do all that I can to save that cathedral."