A five-alarm blaze gutted the 117-year-old église du Centre-Ville on René Lévesque Blvd. near Atwater Ave. Friday night.
The blaze broke out at 5 a.m. at the former Franciscan church, which had been condemned.
Firefighters were unable to determine the cause of the fire, and transferred the investigation to Montreal police.
Squatters were known to stay in the abandoned church.
No one was injured in the blaze, which took 150 firefighters to douse.
"With that building we went on defensive mode, that means we're not taking any chance, we're not exposing personnel," said Montreal fire department operations chief Richard Laporte.
On Saturday, people were seen carrying boxes out of the damaged building next door - also owned by the Franciscans who were renting it out a local business. The convent by the old church was also nearly destroyed and only part of it will be kept standing.
The Franciscans had been trying to sell the land for the past three years. Members of the aging and dwindling order could no longer afford the upkeep on the century-old structure in need of repairs.
"Renovations would have been much too expensive for the few brothers we could have kept there," said Father Marc Le Goanvec.
Le Goanvec said the order was considering destroying the old church as part of the deal for selling the land but also wanted to maintain some of the heritage linked to the building.
With the destruction of the building came a swelling of emotion, said Le Goanvec.
"There's a lot of sadness and I think that's the emotion the friars, the fathers, my community feel today because we are turning a page. It's 120 years of history," he said.
With a report from The Canadian Press
