Canadian real estate developer Ivanhoé Cambridge is suspending construction on a new Montreal office tower after a freelance photographer expressed concerns that the site could be an ancient aboriginal burial ground.

Ivanhoé, the real-estate arm of pension fund giant Caisse de dépôt et placement du Québec, confirmed Sunday it has "voluntarily paused" preliminary excavation work at the downtown Montreal site while outside archeological specialists advise the company on the next steps to take.

The 27-storey tower is being built in partnership with Toronto-based Manulife Financial Corp., and when finished, it will house the insurer's Quebec employees on 11 floors following its $4-billion purchase of Standard Life Canada. It is one of the last significant undeveloped sites in Montreal's core.

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"I think we want to be prudent and responsible," said Ivanhoé spokesman Sébastien Théberge, adding he did not know how long the pause would last.

The company's decision to freeze construction comes after Montreal photographer Robert Galbraith raised concerns with both Ivanhoé and officials in Quebec's culture and communications ministry that the site, a former parking lot between Mansfield and Metcalfe streets, could have valuable historical relics under ground. The situation highlights the sensitivity of questions pertaining to culture and history, as even a single citizen has the potential to influence progress on a $200-million project.

Mr. Galbraith said he believes the construction area, known by its address at 900 de Maisonneuve Ouest, could be part of what historians have identified as the Dawson archeological site. Covering an estimated two acres and studied by then-McGill College director William Dawson in the late 1800s, it was an ancient aboriginal village with remains that included tools and human bones.

Some people believe the site is actually Hochelaga, the St. Lawrence Iroquoian village visited by explorer Jacques Cartier in 1535, and later abandoned. But that has never been proven.

In an e-mailed statement, Ivanhoé said the 900 Maisonneuve site is located outside any designated archeological zone, as it understands them. The company added it has obtained all the permits necessary to proceed with the work and it is "in full conformity" of its obligations, including those related to cultural heritage. It said it will consult provincial officials on the matter.

Mr. Galbraith said that while he is delighted the site will receive a proper re-evaluation by outside specialists, archeological scenes such as these don't fit comfortably into modern constructs like streets and city blocks.

"Are we willing to risk that this site is within defined parameters as we may interpret it today?" Mr. Galbraith asked. "[It's possible] this site is a sort of floating site, meaning it could go as far as Crescent Street," several blocks over.

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Michael Bisson, an associate professor of anthropology at McGill University, said there is only about a 10-per-cent chance at best that even a few scraps of any ancient site remains. That's because big row houses stood there in a more recent past, and digging the foundations for those homes would probably have destroyed what was there.

That doesn't mean the effort isn't worth doing, Mr. Bisson said. "You never can tell. Unfortunately, it's in the middle of a big city. And big cities mean big buildings with deep foundations."

Mr. Galbraith first became aware of the construction preparations when he was walking past the site late last month. He then began making formal inquiries, even following trucks carrying soil to see where they were dumping the material.

He's no stranger to controversies over historical preservation. As a photojournalist, he has chronicled the destruction of some of the world's most prominent archeological monuments, including Afghanistan's Buddhas of Bamiyan.

"When it comes to history, that's the way I am – I'm a fanatic I guess you could say," Mr. Galbraith explained. "Nobody knows their history. That's part of the problem here. … We've lost communication with our past."