Cornwall is the easternmost city in Ontario. It has been home to various people for millennia. On maps of New France, the site is labelled as Pointe Maligne.
The current city was established by United Empire Loyalists, mostly from New York, led by Sir John Johnson in 1784. At that time, it was called New Johnstown after the town in New York from which German immigrants resettled to Canada. It was later renamed after the Duke of Cornwall.
It became one of the first incorporated municipalities in 1834. At that time, work began on the Cornwall Canal which was completed in 1842. It eased navigation around the rapids in the area. This presaged the building of the St. Lawrence Seaway by Canada in the United States in the middle of the 20th century.
The best place to park is at the Rec Centre (where the Flying Frenchmen plaque is). From there, it is easy to walk to these locations and you end up back at the car at the end of your tour.