Prime Minister Justin Trudeau paid tribute to Montreal's founders and highlighted the city's cultural diversity on Wednesday as he joined the festivities in honour of the city's 375th birthday.

"Its francophone roots, its indigenous origins, the contributions of different communities and people who come from all over the world to live here make it a city that is unique in its kind," Trudeau said at a ceremony honouring Jeanne Mance and Paul de Chomedey, the city's founders.

Earlier, Trudeau and Premier Philippe Couillard attended a mass at the historic Notre-Dame Basilica, along with Mayor Denis Coderre and several hundred other guests.

Church bells rang out across Montreal prior to the mass, which was intended to highlight the city's religious diversity.

"Montrealers, more than anyone, know that our diversity is our strength and this mass is a testament to that," Trudeau told the gathering inside the historic church.

That sentiment was echoed by Couillard.

"The gathering this morning expresses the best of ourselves," he said. "Montreal is a city of diversity, with beautiful projects, attracting people from all over the world to put down roots and chase their dreams."

At the homage to the city's founders, which included a performance from the Ecole superieure de ballet du Quebec and Mohawk singers and drummers, Coderre paid tribute to those whose lands on which Montreal was founded.

"We have a duty to remember and recognize the native people, who've also suffered over the centuries of this grand European migration and who have contributed to the edification of society that we live in and who continue to contribute today," Coderre told an audience at an Old Montreal square.

Coderre said that's why the city recognizes it is on unceded Iroquois territory.

"On this day to mark our 375th anniversary, we cannot rewrite history, but we can certainly contribute to the reconciliation between our peoples," he said.

The prime minister also acknowleged the "many errors" that had been made with regard to the treatment of indigenous peoples in the city.

"Part of being an open, vibrant, modern city is recognizing the errors of the past and building always together for a brighter future," Trudeau said.

Trudeau and his wife, Sophie Gregoire Trudeau, as well as several other dignitaries also laid wreaths of flowers at the foot of a statue of de Chomedey as part of the ceremony.

The birthday festivities continued throughout the day and were to culminate with the nighttime illumination of the Jacques-Cartier Bridge.

Trudeau told reporters his birthday wish for Montreal, which was known as Ville-Marie when it was founded on May 17, 1642, is another 375 years of diversity, pride and openness.

He said he is a proud Montrealer even though he was born in Ottawa.

Trudeau said his father, former prime minister Pierre Elliott Trudeau, made it clear where the family came from.

"I grew up in Ottawa, I was born in Ottawa, but my father was a Montrealer and he would bring us here quite regularly," he said. "He would tell us, 'No, you live in Ottawa but you're Montrealers. You just don't really know it yet.'

"So when I arrived here at the age of 13 after my father left politics, it was like coming home."