The vity of Vannes, located as it is in the heart of a drowned river valley, is indebted to the Romans for providing solid foundations on which they could build a fortified city in the Middle Ages. Extending the city limits to include the port actually doubled the city's surface area.
Within the city itself, numerous timber-framed houses adorn the narrow streets around the cathedral, an edifice which was rebuilt after the 15th century. This "wooden city" is complemented by stone construction in the classical period. This was the heyday of maritime trade in the area and additional wharfage was built to accomodate this growth.
Yet, this trade system crashes in the 19th century. The 1860-1870's saw the local prefecture begin the construction of new public buildings and this provides the area with an economic boost, thanks to the development of railways which helped the local industries.