Canadians around the country attended celebrations to mark the country's 145th birthday on Sunday, including a massive bash on Parliament Hill which ended with a large fireworks display.

Prime Minister Stephen Harper attended the ceremony in Ottawa along with Gov. Gen. David Johnston.

Thousands of people were forced to stay on Wellington Street by RCMP, who let only a trickle of visitors past the gates for the noon show, the CBC's Peter Mansbridge reported.

Johnston carried out an inspection of the Guard of Honour, and the crowd watched a fly-past by the Snowbirds, before Canadian opera singer Julie Nesrallah performed God Save the Queen.

Jully Black was next on stage, singing O Canada.

As Harper took to the podium, he sent "best wishes" to the Queen for her Diamond Jubilee, marking 60 years on the throne.

He also said Canadians have much to be proud of, including a "strong and growing economy, a caring and compassionate society and our Canadian Olympic and Paralympic athletes who are heading to London ... and the courage and devotion of our men and women in uniform."

Later, there were performances by Feist, Simple Plan, Roch Voisine and Donny Parenteau.

The Grey Cup, which celebrates its 100th birthday this year, was a focus of the day's festivities with a video montage of scenes from past championship games.

Harper reflects on War of 1812

The show featured actors playing key figures from the War of 1812, one of the themes of this year's celebrations. This year marks the bicentennial of the war.

In his Canada Day message, Harper made special mention of the War of 1812 as a source of pride.

Gov. Gen. David Johnston, left, with Prime Minister Stephen Harper and Chief of the Defence Staff Walter Natynczyk attend noon-hour Canada Day celebrations. (CBC)

"It's fitting that this year, that we should reflect upon the military struggle that made Canada possible, the War of 1812," he said. "Almost exactly two centuries ago, an American invasion of Canada was launched."

"Our ancestors, English, French, Aboriginal, people of all backgrounds joined in the fight for Canada. In doing so, they created a common sense of nationality based on diversity and they laid the basis for the parliamentary federation of freedom, democracy and justice that is our inheritance," Harper said.

In the Governor General's message, he said from the moment of Confederation in 1867, Canada has been a unique and challenging experiment.

Johnston said the nation resembles a giant family that each day displays a commitment to unity, diversity, excellence and equality of opportunity.

Speaking at the close of the noon-hour ceremonies, Johnston said Canadians have a lot to be thankful for.

'A better future'

"All Canadians want to create a better future for this country," he said.

Roch Voisine performs for the Parliament Hill crowd. (CBC)

Across Canada, more than 30 special citizenship ceremonies were also held, swearing in over 1,500 new Canadians.

Shabnam Clark was one of many new Canadians on Parliament Hill.

She received her citizenship last year after arriving from Iran and said she wanted to join the celebrations because her newfound country offers her so much.

"I like that Canada is a very peaceful country," she said.

With files from The Canadian Press