"Atop Cap Diamant (Cape Diamond), at the city's highest point, the Citadelle overlooks Old Québec, the St. Lawrence River, and the Plains of Abraham. There have been defensive structures here as early as the French period—in fact, the location of Québec City was chosen because Samuel de Champlain saw the strategic advantages that Cap Diamant offered. The fortifications you see today, however, date to the 19th century: They were built after a failed attempt by Americans to conquer Québec City during the War of 1812. Students of World War II history may be familiar with the Citadelle as the site of the Québec Conferences, when Winston Churchill, Franklin Delano Roosevelt, and Canada 's prime minister, William Lyon Mackenzie King, met to plan their countries' strategies during the war. The Citadelle is still an active military base; the museum inside is devoted to the 22nd Regiment, which makes its headquarters here."