Buckminster Fuller's geodesic dome is an iconic structure that's instantly recognizable. It was created for Montreal Expo in 1967 and has stayed in place since then as a monument to 20th century optimism. It's been used as a film set, featuring in Battlestar Galactica among other productions.
Environment Canada bought the dome in 1990 for conversion into a museum of the Great Lakes and the St Lawrence River, and it evolved in 2007 into its current incarnation as the Biosphere. It's a set of buildings placed inside the original steel frame, featuring interactive exhibits about water, climate change, the air we breathe, eco-technology and sustainable development. The displays are creative, especially the section on forests, focusing on the beauty and wonder of the world as it is, as much as the need for action to preserve it.