Canadian Press has a short piece about Holling’r selling the building at 10 Toronto St. In it there is this description of the history of the building.

[...] it intends to do restoration work on the distinctive three-storey stone building, which was built in the 1850s.

It was built for the Province of Upper Canada — Ontario before Confederation — as a post office and was later used by the Bank of Canada.

I thought that it was strange because I didn’t think Upper Canada existed in the 1850s.

The Union Act of 1840 amalgamated Lower Canada and Upper Canada to form the province of Canada made up of the provinces of Canada East and Canada West.

It makes me wonder where the reference in the story came from, did someone extrapolate from the date, or was the name related to the building a holdover from after amalgamation, or what.