Aveiro will start between the 10th and 12th centuries at the mouth of the Vouga River as a small fishing village. The estuary already existed as a result of the formation of the dunes that were closing the exit of the waters of the river to the sea. The estuary is the main geographical feature that defined the type of activity of the population that grew here; a small inland sea, abundant fish that created an underwater flora, the moliço, an inexhaustible source of fertilizer for the farming of the nearby agricultural land. In addition it had the richness of salt. The salt flats in Aveiro were already cooled in the 10th century in the will of Countess Mumadona Dias. In the 16th century, vessels came from northern European ports to seek salt which was later used to salt the herring they exported to northern Europe. In the 13th century, Aveiro was elevated to the category of a village, developing the settlement around the main church, dedicated to S. Miguel and located where today is Praça da República, with this temple being demolished in 1835. Later, D. João I, on the advice of his son, Infante D. Pedro, who, at the time, was a grantee of Aveiro, had it surrounded by walls that, in the 19th century, were demolished, part of the stones being used in the construction of the new bar piers. In 1434, D. Duarte granted the village the privilege of holding an annual free fair that has reached our days and is known as the March Fair. At the end of the 16th century, beginning of the 17th century, the instability of vital communication between the Ria and the sea led to the closure of the canal, preventing the use of the port (see Porto de Aveiro) and creating unsanitary conditions, caused by the stagnation of the waters of the lagoon, causes that caused a great decrease in the number of inhabitants - many of whom emigrated, creating fishing villages along the Portuguese coast - and, consequently, were the basis of a great economic and social crisis. It was, however, and interestingly, in this phase of recession that, in full Philippine domination, one of the most notable temples in Aveiro was built: the Misericórdia Church. In 1759, D. José I elevated Aveiro to the city, a few months after having condemned his last duke for treason on the scaffold, a title created in 1547 by D. João III. For this reason, and at the request of some notable people in the city, the new city was given the name Nova Bragança instead of Aveiro, by Alvará Real of April 11, 1759. With the fall of the power of the Marquis of Pombal, after D. Maria I became queen in 1777, so she sent the city back to its previous designation.
