This looks to originally be the St Patrick school; it then became École Mille-Îles. The french-language school moved to the west-end suburbs in 2018. There was also an adult education "Open Book" which is now on Princess St in a stripmall storefront. No idea what (if anything) is here; there was some talk of using the land for housing, but a web search on "158 Patrick St" finds nothing interesting beyond "it used to be a Catholic school".