The double ramparts of Carcassonne stretch three kilometres around a hilltop settled by Romans in the first century BCE, fortified by Visigoths in the fifth century, expanded by Trencavel viscounts in the twelfth, and methodically restored by Eugène Viollet-le-Duc between 1853 and 1879. By 1850 the medieval Cité had decayed so thoroughly that municipal authorities debated demolition; Viollet-le-Duc's intervention saved fifty-two towers, the Château Comtal, and the Basilica of Saints Nazarius and Celsus, earning UNESCO World Heritage designation in 1997. The architect's conical slate roofs remain controversial among purists who argue that original Languedoc towers wore flat terracotta tiles, yet his vision created the silhouette recognized worldwide today. Ninety-two kilometres separate Toulouse and Carcassonne, a distance Roman engineers covered in two days on the Via Aquitania, medieval pilgrims in three on the Chemin de Saint-Jacques, and modern coach services in ninety minutes on the A61 autoroute. The route crosses the Lauragais plain, a golden corridor of sunflower fields and wind turbines between the Pyrenees foothills and the Montagne Noire. Carcassonne's strategic value derived from this geography: the citadel commanded the narrowest passage between Atlantic and Mediterranean watersheds, a chokepoint contested in the Albigensian Crusade of 1209, the Hundred Years' War, and France's 1659 annexation of Roussillon. When the Treaty of the Pyrenees pushed the Spanish border southward, Carcassonne lost military relevance; prosperity migrated to the Bastide Saint-Louis across the Aude River, leaving the upper town to decay for two centuries. Today the Cité receives four million visitors annually, making it France's third most visited monument after the Eiffel Tower and Mont-Saint-Michel. The Château Comtal, built by the Trencavel dynasty in the twelfth century and reinforced by Louis IX in the thirteenth, anchors the complex. Its inner courtyard displays Gallo-Roman fragments and medieval millstones; the rampart walk offers unobstructed views across the Aude valley to the Pyrenees. The Basilica of Saints Nazarius and Celsus combines Romanesque nave with Gothic transept, its stained glass dating to the thirteenth and sixteenth centuries. Rue Cros-Mayrevieille and Rue du Grand Puits retain cobblestones and timber-frame facades reconstructed by Viollet-le-Duc using medieval building techniques. Evening illumination, installed in 2008, highlights the ramparts' layered construction: Roman foundations in dark stone, Visigothic repairs in brick, and twelfth-century additions in pale limestone.