Sitting by a natural harbor at the mouth of the Penfeld River in western Brittany, the city of Brest has a rich maritime history that stretches from the Middle Ages to today, as it is home to the main French naval base in the Atlantic. Brest’s strategic importance was first established in the 1600s, when Cardinal Richelieu created a naval base and arsenal here. Throughout the Napoleonic Wars, warships were produced in its dockyards. During World War I, Americans maintained a naval air station in Brest, then Germany took control of the city during World War II and stationed U-boat submarines in its harbor. Though much of the city was destroyed in 1944 after an Allied invasion, one of Brest’s most important sites escaped the bombing: the Château de Brest, a 13th-century castle that’s the oldest structure in town. Just across the Penfeld River stands the 14th-century tower Tour Tanguy; inside is a museum that showcases the history of the city prior to World War II, with dioramas, photographs, postcards and other objects.