The City of Toronto Archives at 255 Spadina Road provides a terminal for the Toronto Property System database. You can search the current Toronto Assessment Rolls to identify property owners. Search by property address or street name to find the owner of the property. (Hint: The entire hydro corridor is listed under 1 Bridgman). Printing is $1.04 per sheet but you can take a picture of the screen for free.
Historical Assessment Rolls are available on microfilm in the main reference room.
The City of Toronto Archives also has building permit information from 1891-1970.