Rouen (UK: , US: ; French: [ʁwɑ̃] (listen) or [ʁu.ɑ̃]) is a city on the River Seine in northern France. It is the prefecture of the region of Normandy and the department of Seine-Maritime. Formerly one of the largest and most prosperous cities of medieval Europe, the population of the metropolitan area (French: aire d'attraction) is 702,945 (2018). People from Rouen are known as Rouennais.

Rouen was the seat of the Exchequer of Normandy during the Middle Ages. It was one of the capitals of the Anglo-Norman dynasties, which ruled both England and large parts of modern France from the 11th to the 15th centuries. From the 13th century onwards, the city experienced a remarkable economic boom, thanks in particular to the development of textile factories and river trade. Claimed by both the French and the English during the Hundred Years' War, it was on its soil that Joan of Arc was tried and burned alive on 30 May 1431. Severely damaged by the wave of bombing in 1944, it nevertheless regained its economic dynamism in the post-war period thanks to its industrial sites and its large seaport, which today is the fifth largest in France.

Endowed with a prestige established during the medieval era, and with a long architectural heritage in its historical monuments, Rouen is an important cultural capital. Several renowned establishments are located here, such as the Museum of Fine Arts, the Secq des Tournelles museum, and Rouen Cathedral.

Seat of an archdiocese, it also hosts a court of appeal and a university. Every four to six years, Rouen becomes the showcase for a large gathering of sailing ships called "L'Armada"; this event makes the city an occasional capital of the maritime world.