The Association of Provincial Land Surveyors of Ontario
The provincial land surveyors, successors to the deputy provincial surveyors of Canada West, were appointed to map the province and mark out townships, roads and lots for settlement. They were first organized on 23 February 1886. From 1887, ten consecutive annual meetings were held on this site. The inaugural meeting of the Association of Ontario Land Surveyors was held in the Canadian Institute on this site on 23 February 1892.
Plaque via Alan L. Brown's site Toronto Plaques. Full page here.