Doors Open Toronto is an event that features 150 buildings of architectural, historic, cultural, or social significance that opens their doors to the public. Most of these buildings typically do not allow the general public to gain access.
The King Edward Hotel was Toronto's first luxury hotel built in 1903. In more recent years, it became well known for the Crystal Ballroom, which is a massive grand ballroom that had been abandoned for several decades. This was a regular site for eager urban explorers. Naturally, it had to be the first place on my list of buildings to visit.
Panorama of the Crystal Ballroom, full version can be found here.
Looking down from the Crystal Ballroom (they immediately closed the window seconds after I took this shot). You can also see the line-up of people from the reflection on the building across the road.
Commerce Court North was the tallest building in the Commonwealth from 1931 to 1962 at 34-storeys. The immense banking hall was modeled after the Baths of Caracalla in Rome, and now houses the Canadian Imperial Bank of Canada (CIBC).
City Hall -- home of municipal government suits. It does have a nice 27-storey observation deck, however.