Glengarry Cairn

This is a list of National Historic Sites in the province of Ontario. As of July 2021, there were 274 sites designated in Ontario, 39 of which are administered by Parks Canada. Of all provinces and territories, Ontario has the greatest number of National Historic Sites, and the largest number under Parks Canada administration, with a dense concentration in southern Ontario. The five largest clusters are listed separately:

· List of National Historic Sites in Hamilton

· List of National Historic Sites in Kingston