The Fort was built by the French at the time when the French and English were fighting for control of the Canadian maritime area. The fort is huge, probably covers about 20 acres. We took a guided tour with a college student--a little over an hour in duration, and very informative. We were told how the fort was built to be impenetrable from the sea, but how the British attacked from behind by land. The tour explained what soldiers' lives were like, and we were guided through the chapel, warehouses, governor's house, financial administrators house, engineers house, soldiers bunkhouses.
The guide provides a lot of history and interesting information during the tour. When on your own after the tour there is much more to see. There are also several places for food, drink, souvenirs etc. We had a lunch at Hotel de la Marine on the site serving food of the times in costume. It was a decent meal and the location was interesting. We had meat pie, salads and cheeses. You could spend anywhere from 2 hours to a full day here. We spent about 4 hours.