world fair in Montreal, Canada
You will find many links for Expo 67 sites at Wikipedia.
Here are a few sources I used for collecting the images:
Expo 67 postcard gallery, Expo 67 (un-)Official Guide, Expo 67 - a virtual experience, The Canadian Design Resource: Expo 67
Thank you all!
And finally, let me introduce Lillian Seymour. This lady visited Expo 67 and you can see her polaroid snapshots here.