I flew over this building this weekend, and I have no clue what in the world it could be.
If the link isn’t working, it’s a building that looks like an asterisk from above - six equal arms radiating from a center bit. It’s on a big chunk of land, almost like a park (?) and it’s accessed by Gouin boulevard, east of Autoroute 15.
I don’t know Montréal at all, but from looking at the Google Maps image, I’m willing to bet that it’s a prison.
There appear to be substantial walls around it. The asterisk would be the cell blocks, with exercise yards between, built on a plan somewhat influenced by the Panopticon. And the other buildings would be guards’ quarters, the administrative building, the heating plant, etc.
I used to take the bus by there all the time. You’ve also got Tanguay Prison (a women’s facility) to the southeast of it, and the main Montreal office of the Société d’assurance d’automobile de Québec (our DMV) just past that. <Insert your own joke about ex-cons and bureaucrats here.> Your map also shows the “passerelle de la regie”, a weird little looped overpass over Henri-Bourassa Boulevard that exists for no other reason than to confuse people taking driving exams.