The old Reitman building eventually became the Softimage headquarters.
The oldest part of the building dates back to 1921 and housed different clothing manufacturers, until 1951 when it became the Reitman’s headquarters and distribution center for hats, gloves, and lingerie. Softimage moved into the building in the mid 90s.
Here’s a few pictures of the Softimage building and its signage (sent to me by Sven C, thanks!).
eX-SI 
Softimage was there way before the mid 90s, As far as I can remember they were on the 3rd floor in 1988 when I first met with Daniel Langlois and Richard Szalwinski.
-mab
Ah, I wasn’t sure about the dates, thanks. All I know is I moved up there from the Just for Laughs building in the late 90s (and I was the first of the doc group to make the move).