This photo shows a number of the restored buildings in Fortress Louisbourg in the foreground, with Louisbourg Harbour in the middle ground, and the modern village of Louisbourg on the opposite side of the harbour.
Louisbourg Harbour was the main reason the French chose to build a fortress here. This description says that it is two miles long and a half a mile wide with a depth of six to ten fathoms and characteristics that made it very defensible against water-borne attacks. It provides a safe anchorage and a year-round ice-free port that continues in commercial use to this day. During Louisbourg’s heydey in colonial times, the harbour was a very busy place, often filled with more than four hundred boats from France and trading vessels from the American Colonies to the south.