Joe Shuster was the co-creator and original artist of Superman. Shuster was born and raised in Toronto, where he was a paper boy for The Toronto Star. (For those of you who know Toronto well, he lived in and around Kensington Market.)
In the original version Superman's mild-mannered alter ego, Clark Kent, worked for The Daily Star, which was patterned after The Toronto Star. The newspaper's name in the strip was changed later to The Daily Planet.
To clarify the preceding passage, I should add that The Toronto Star was The Toronto Daily Star when Shuster was growing up.
Superman co-creator Joe Shuster modeled the look of Metropolis after his home town of Toronto, Ontario, Canada (though Metropolis was never depicted as a Canadian city).
Other than the Daily Planet, are there any other specific Toronto landmarks that are seen or referenced, either in name or appearance, within Metropolis in the comics?