So I was curious as to the significance of this building and did some of my own googling with the following results:
at
http://www.internvest.com/properties.htm I found:
Lumsden Building
Toronto, ON
The Lumsden Building is a historical office building located on the northeast corner of Yonge and Adelaide. The ten storey building is completely renovated, offering both prime office and retail space. Located on the Yonge subway line and across the street from the PATH system, the Lumsden building stands in the core of Toronto’s financial district.
Owned and Managed by Internvest
Also at
http://www.answers.com/topic/dominion-bridge-company
I discovered that the building was constructed in 1910 with the assistance of (and this should interest our bridge fanatics) the Dominion Bridge Company.
The city of Toronto designated it as a heritage site in 1978 and lists it as being built in 1909, rather than 1910:
http://app.toronto.ca/heritage/browseLetter.do?letter=Y
Lumsden Building, 1909, J.A. MacKenzie at 2-6 Adelaide St. E. -adopted by City Council on June 20, 1973 DESIGNATION BY-LAW PASSED BY CITY COUNCIL on Jan. 16, 1978 (designation plaque - 1979)
And that's about all I could find.