Ontario Place was/is adjacent to downtown Toronto, and well if you were to drive straight north without backtracking west on the QEW to reach the 427 to eventually get to the 401, it's a distance of around 27 km or 17 miles.
Ontario Place's Marina, as well as the large concert venue, the Molson Amphitheatre (now the Budweiser Stage), and Atlantis pavilions (which used two of the pods at the time) survived the 2012 closure. The cinesphere closed in 2012.
The Molson Amphitheatre ended up "stealing" the big shows from Kingswood in Canada's Wonderland in the mid 1990s. Similarly to how Riverbend did the same thing with the Timberwolf Amphitheater.
Atlantis has now completely shutdown, it was used for private events I do believe.
The Cinesphere CLOSED in 2012, but it reopened as of November 2017 with constant showtimes. During the older days of the CNE, the IMAX documentaries were usually only played in the Cinesphere and not "regular" movies. The Ontario Place grounds are completely free to walk around, although I do believe much of the East Island looks different now.
http://ontarioplace.com/en/cinesphere/