The American pavilion is one of the few structures left, but it almost didn't survive. In 1976, it was almost destroyed by fire. Today, it's now known as the Montreal Biosphere, and has been turned into an environmental museum. I visited the Expo site in 1979. Here's my two shots of the burnt-out buckyball, before it was repaired.
In late 1978 or early 1979, a small second unit crew went to Montréal and filmed some scenes for the episode "Greetings From Earth" of the original Battlestar Galactica series. While many of the scenes were just establishing shots of a decayed futuristic landscape, series star Dirk Benedict and guest star Bobby Van did travel to Montréal to film a couple of scenes near the ruins of various pavilions. You can see the Man the Provider Pavilion in the background of this scene. By the time of my visit in 1979, Île Notre Dame was closed, and we could see the pavilions across the river being dismantled. I took two last pictures....