Metro Convention Centre, Toronto
Nobody even called them green roofs, they were just landscaped decks, like this one over the buried portion of the Metro Convention Centre in Toronto, a political expediency where they wanted to expand but the land was designated for a park, so they put it underground and landscaped the top of it. This was before the term "green roof" was in common use, or they would have made a virtue of it, instead of a necessity. It makes a lousy park and a worse convention centre, but you have not seen the last of this idea.
Credit: Google Maps