Our Lady of Assumption, Windsor’s oldest church, will close its doors to hundreds of parishioners this weekend.

The closure comes after two campaigns to try to save the historic site, which is 169 years old.

Church fundraisers say the money is there and they're making one last effort before parishioners go their separate ways on Sunday.

Since 2009, organizers led two campaigns to raise enough money for repairs and restoration.

The group heading the fundraising wonders why the Diocese of London hasn’t reversed the decision.

“I think it's a travesty and it is a sad day for Windsor to be losing this historic icon,” says fundraiser Kim Spirou.

“The money is there; the will is there of the parish to see it through. The question needs to be asked to the bishop. He needs to respond to these very compelling questions."

Fundraising efforts to repair the century's old building brought in more than $10 million.

Then, once the diocese announced Assumption would close in August , officials were made aware of a new $10 million anonymous contribution.

The diocese says it needs to do its due diligence before moving forward.

“If it was easy, we would have been able to do it. But right now, it's complex and we have a limited amount of resources here and we have 120 other parishes to make sure that we're serving as well,” says diocese spokesperson Mark Adkinson.

A letter was issued to the parish priest at Assumption by the council earlier this week seeking answers.

“I know there's a lot of concerns from parishioners who have been there for a long time. There's deep roots, people have been there with their families for generations,” says Kevin Alexander, chair of Assumption’s parish council.

“We will receive a decision by mid November and we remain hopeful that it's positive and that we're able to have the parishoners move back into the church,” he says.

The diocese is still willing to consider keeping the church open.

“If this proposal works out, and something else comes forward to restore the church, we will start that process,” Adkinson says.