Nantes was pretty lucky during World War II: unlike a lot of French cities, it wasn’t totally destroyed by bombings. The city still has a rich heritage, dating right back to the Gallo-Roman period.
The medieval area is the Bouffay, with the Castle of the Duchy of Brittany and the many old buildings surrounding it. The 18th Century was the golden era for the city (slave trade…), and a lot was built during this time, notably Place Royale and Place Graslin. Later in history, Nantes was also an industrial city in the era of the first naval shipyards: the LU Tower is a reminder of that time.