Vannes is a commune situated in the Morbihan department of Brittany, in northwestern mainland France. It lies on the Gulf of Morbihan at the mouth of the Marle and Vincin rivers, positioning it as a market town linked to the sea. The city serves as an administrative center within the region and is recognized as the fifth-largest city in Brittany. Its location makes it a significant hub for regional connectivity and maritime activity.

Founded over 2,000 years ago by the Veneti, a seafaring Celtic people, the settlement was later known as Darioritum under Roman rule after their defeat in 56 BC. The town became a center for an independent principality under the Breton name Gwened following the arrival of immigrant Britons from the fifth to seventh centuries. It served as the capital of the Duchy of Brittany in the fourteenth and fifteenth centuries, with notable fortifications established by Duke John IV.

The city is defined by its medieval village, surrounded by old walls and gates such as Porte Calmont and Porte Saint-Jean. Key landmarks include the Gothic Cathedral of St Peter, the Château de l'Hermine which was a residence for Dukes of Brittany, and the archaeological museum in Château Gaillard. The historic center features numerous timber-framed houses and cobblestone streets, while the port area offers access to the surrounding Gulf.

Vannes attracts visitors with its rich history, including the Franco-English Tournament of 1381 and its role in the Breton War of Succession. Cultural attractions include the Musée de la Cohue for fine arts and various churches like St Patern and Saint-Yves. The town hosts festivals such as Bastille Day celebrations with costumed parades and offers boat sailings to islands in the Gulf of Morbihan, drawing tourists interested in heritage and maritime scenery.

The population of Vannes was 55,790 as of 2023. It is accessible via the TGV high-speed rail, connecting to Paris in 2.5 to 4 hours, and by highways N165 and N166. The city features a public bicycle rental program called Vélocéo and local bus networks operated by Kicéo. Its climate supports tourism year-round, with the tourist office adjusting hours seasonally to accommodate visitors exploring the medieval architecture and local pottery.