The Romans named it Aquae Flaviae around 78 AD after their discovery of thermal springs and nearby gold deposits. Its fertile surroundings and strategic position marked its early history with various battles and sieges between wandering tribes. The Portuguese eventually took possession of the town from the Moors in 1160. The town was given to Nuno Álvares Pereira by King João I as a reward for defeating the Castilians at the battle of Aljubarrota in 1385. The city was subject to a failed attack in 1912 from Royalists based in Spain.
This City is situated in a fertile plain on the upper reaches of the River Tâmega that runs to the south and east to Porto. Its present day fame lies in its reputation as a Spa Town and the local cured hams. The old part of town is to be found around the main square with the ruins of a 14th Century Keep, all that remains of the former fine castle built for Nuno Álvares Pereira. The walls of the fortress are a fine example of the principles used by the French military defensive architect Count de Vauban. Of the two churches standing on the square the Misericódia is probably the most interesting with its large 18th Century tiled panels depicting scenes from the Bible.
In the Keep is a small museum with armor and memorabilia of the 1912 attack. In the Museu da Região Flaviense there is an interesting collection of items from local archaeological sites. The fine sixteen-arched Roman bridge spanning the River Tâmega is from the period of the Roman Emperor Trajan. Close to the centre is one of the warmest natural springs in Europe reaching up to 73º C (163ºF). The area is also famed for its production of cured ham.
During the time of its occupation by the Romans, the city of Chaves was known by the name of "Aquae Flaviae", given to it by the Emperor Titus Flavius Vespasianus (Vespasian), who recognised the excellent quality of the thermal springs located here. The healing properties of these waters, the warmest in Europe with a temperature of roughly 73º C at their source, are still greatly appreciated and the spa is an extremely popular one. Standing on the banks of the River Tâmega and close to the border with Spain, Chaves has always been very important from the military and strategic point of view. The city heroically withstood annexation by Castile in the sixteenth century, and later, in the nineteenth century, it was here that the invading Napoleonic troops suffered their first defeat on Portuguese soil. Remaining as a testimony to the city´s defensive importance are the castle and its keep, as well as the mediaeval quarter contained within the city walls. Chaves is also famous for its richly varied cuisine, and particularly for its sausages and smoked ham.