The capital of Normandy is Rouen, a city located in northern France on the River Seine. It has a long history, having been founded by the Gauls in the 1st century BC and later becoming an important trading center during the Middle Ages. Rouen is also known for its Gothic architecture, including the Notre-Dame Cathedral, which was built in the 13th century. Today, Rouen is a major port city and a popular tourist destination.