The Seine was declared a UNESCO World Heritage site in 1991, yet its role as Paris's ceremonial artery dates to the city's Roman founding in 52 BCE. By the nineteenth century, the river had become the axis around which Haussmann's renovated capital organized itself — bridges multiplied, quays widened, and the 1867 Exposition Universelle established boat services as both transport and spectacle. Today, the fleet of glass-roofed vessels departing from Port de la Conférence continues that tradition, though the cargo is now sightseers rather than freight. A boat tour Paris night reveals the city's architectural chronology in compressed form. The medieval buttresses of Notre-Dame, still under restoration following the 2019 fire, anchor the eastern narrative. Westward, the Louvre's Renaissance wings give way to the Beaux-Arts grandeur of the Musée d'Orsay and the iron filigree of the Eiffel Tower, completed in 1889 as a temporary structure and now the most-visited paid monument in the world. The tower's five-minute sparkle sequence, triggered on the hour after sunset, draws camera shutters across every deck. Evening departures between 20:00 and 22:00 capture the city at its most theatrical. Floodlights illuminate the Conciergerie's Gothic towers, the Assemblée Nationale's columned portico, and the thirty-seven bridges that stitch the Left and Right Banks together. Most Seine river cruises follow a one-hour westward loop from Pont de l'Alma to the Statue of Liberty replica on Île aux Cygnes, then return eastward past the Musée d'Orsay and Institut de France. Multilingual audio commentary, available on most vessels, layers historical context over the unfolding panorama. Bateaux-Mouches, the oldest operator still running from the original 1949 dock, maintains a fleet of twelve boats, each carrying between 350 and 600 passengers. Smaller competitors offer crêpe tastings or live accordion music, but the essential geometry remains constant: a low-angle vantage point that renders Paris's skyline as a horizontal frieze, best appreciated when artificial light replaces daylight and the city's monuments emerge as illuminated monuments against the autumn sky.