An 8-minute film by Julian Biggs from 1964 (IMDB says 1965) which turns the streets of Montreal into post-apocalypse tableaux.
This short black-and-white film shows eerie scenes of a downtown without people. The effect is disturbing. The camera shoots familiar urban scenes, without a soul in sight: streets empty, buildings empty, yet everywhere there is evidence of recent life and activity. At the end of the film we learn what has happened.
Being a film funded by the National Film Board of Canada, the only place to see this would appear to be on their website. That would be fine if the streaming worked but every time I’ve tried using the latest iteration of their site the connection seizes up. Other viewers may have better luck.