 During the Gothic period, most churches were built with a single aisle on each side of the nave, such as Salisbury Cathedral, but some had double aisles with the outer lower than the inner, such as Bourges Cathedral.In the South of France Gothic churches are sometimes just a single high, wide hall, with tall windows but no aisles, and the lower stage giving a robust fortified appearance, such as Albi Cathedral.Gothic churches of the Germanic tradition, like St Stephen of Vienna, often have nave and aisles of similar height, without clerestory, and are called "Hallenkirche".