From Wikipedia:
Richard Buckminster “Bucky” Fuller (July 12, 1895 – July 1, 1983)[1] was an American architect, author, designer, futurist, inventor, poet and visionary. He was the second president of Mensa.[2]
Throughout his life, Fuller was concerned with the question “Does humanity have a chance to survive lastingly and successfully on planet Earth, and if so, how?” Considering himself an average individual without special monetary means or academic degree,[3] he chose to devote his life to this question, trying to find out what an individual like him could do to improve humanity’s condition that large organizations, governments, or private enterprises inherently could not do. Continued here.
He designed the geodesic dome at Expo ’67 that housed the American pavilion. In 1976 a fire burned the dome’s paneling and it remained abandoned until the early ’90’s when it was renovated into the Biosphere,
(c) 2001 Cédric THÉVENET)
which opened in 1995, and is dedicated to sustainable issues surrounding water, the environment, and the Great Lakes/Saint Lawrence water system.
I have had the great pleasure of visiting this noble structure in three of it’s formats. Here are some images from 1988.
It is not often you will ever see someone paint the name of the architect on the side of the building, so this gesture has always resonated very nicely with me. It is an appreciation of things on a grand yet very human scale.
PostArctica 
By far my favourite structure on the island, closely followed by the Calder piece which binds together the merry piknic electronik party goers throughout the summer. I had the unique opportunity to attend a wedding reception in the BioSphere/Buckyball about 5 years ago. That was a real trip, stepping out of the tented dining hall into the moonlight surrounded by sphere of steel.
Sounds very interesting. There is a good feel to the “buckyball”. Olympic Stadium is super iconic but there just isn’t enough good feelings that go with it, so I agree that the dome probably is number one.