Long before Jack Layton rode his "orange wave" into the House of Commons, the NDP leader was an affable Toronto city councillor bent on making a difference.

After a successful run for city council in 1982, Toronto came to recognize Layton as tireless crusader for the homeless and sustainable urban development.

Now, as word spreads of Layton's death early Monday morning, Torontonians are mourning the loss of a man who became an integral part of the city's history.

Hundreds gathered in front of City Hall Monday afternoon to pen messages of condolence, and to thank Layton for his contribution to the city and the country. Many scrawled messages in chalk along a wall in front of the building.

"It's pretty obvious by the number of people here that he was someone whose views and whose passion brought people together," said one mourner. "He was someone with a lot of integrity."

City Councillor Janet Davis (Ward 31) remembered Layton as an inspiring person with boundless energy.

Meanwhile in an interview with CTV News Channel Friday evening, former mayor David Miller recalled Layton's battle with cancer.

"He was with his illness as he was with other issues: he was optimistic, he was tough, he was strategic, he was smart about how he fought it. And you know he was also very, very courageous," Miller said.

"Being the leader of a national party and campaigning in an election is gruelling; to do it while you're fighting cancer is unbelievable. And that courage sets a tremendous standard, let alone his political accomplishments from a career that spanned three decades."

Toronto-Centre MP Bob Rae told reporters on Friday that Layton "was an extraordinary guy to have in our public life."

The Liberal MP described Layton as both feisty and approachable, saying that he treated constituents the same way he treated his family and friends.

"He never took things personally, he never saw things personally; he was always a complete professional," Rae said.

Layton entered municipal politics in 1982 when he made a successful run for the role of Toronto alderman. He went on to serve on city council until 1991, when he ran for mayor and placed second behind June Rowlands.

Even after his first municipal defeat, Layton remained in political life. He joined Toronto's newly amalgamated city council in 1998 and was re-elected in 2000. He gave up his seat in 2003 after being elected as leader of the federal NDP.

"[Layton] had extraordinary resilience and an ability to come back from defeat both political and his personal challenges," said Rae.

Condolences from constituents

Bouquets of flowers and notes of condolence sat outside Layton's Toronto-Danforth constituency office on Broadview Avenue on Monday morning, early evidence that the city was in mourning.

One card from a rapidly growing pile sitting outside the office read, "Thank you for this sense of loyalty and commitment to this city and to this country."

By Monday evening, mourners were lining up down the street to leave bouquets of flowers and other small gifts on the steps of his office.

CTV's John Musselman spoke to several mourners who had stopped by the Layton's office to express their grief.

"How can you replace a guy like Jack?" said one constituent. "I mean, he did so much for the city, so much for the party and he had a vision."

Another local supporter told CTV Toronto that he felt like he lost his best friend.

"It's a very sad day. He's going to be sorely missed," he said.

"He's going to be sorely missed," he said.

Linda Chamberlain, who lives a few doors down from Layton's office, said she hopes that other political parties will support Layton's legacy "by doing the hard work that he's done for all these years to help us Canadians."

"Today is a sad day," she told CP24.

A city in mourning

Meanwhile, the flags outside Toronto City Hall, Metro Hall and several city civic centres waved at half-mast in Layton's memory.

Mayor Rob Ford spoke to reporters about Layton's passing, describing him as a humble public figure.

"He never let the job go to his head. Some politicians are conceded and arrogant. He was not one of them," said Ford, who served on city council with Layton.

"He'll be missed -- it's very, very unfortunate. But I just want to thank him for what he taught me."

Former Toronto mayor Mel Lastman spent over two decades working with Layton at City Hall and also said he was saddened by news of his death.

"I saw firsthand his deep commitment to helping improve the lives of so many people especially those who were struggling and living on the street," Lastman said.

Some local supporters have started stopping by the home Layton shares with wife and Trinity-Spadina MP Olivia Chow.

One woman who signed her name as Patricia, left a card outside the home that read, "Jack raise a little hell in Heaven.....We need more angels"

Twitter users across Toronto have also taken to the social networking site to organize a spur of the moment memorial in Layton's memory.

Starting at 4 p.m., hundreds of Torontonians showed up in from of City Hall in a vigil to mark Layton's passing. There was a public reading of his goodbye letter.

"I'm absolutely shocked, but I know that Jack Layton has inspired many people," Shamini Selvaranum, one of the organizers, told CTV News.

The vigil idea started with a few tweets on Twitter, the social messaging service. Someone then posted a Facebook group, she said.

"All these people showed up, which means he's not just a politician. He's the most real thing in Canadian politics," Selvaranum said.

With a report from CTV's Nathalie Johnson