After the former site of the council’s meeting was occupied by the church of Santa Maria Maior (today the Cathedral), this Town Hall was built out of doors at the beginning of the 20th century. It is, like so many other similar constructions in the Hispanic Northwest, a two-story building, with the “Câmara” on the main floor where the council met and on the ground floor an archway to shelter people and scribes who wrote here, for the illiterate, requirements and other documents addressed to the Chamber. Today it is a cultural space at the service of the city.

The building of the City Hall of Viana do Castelo is located in the historic center of Viana do Castelo, in the square where the old gate of São Tiago was located, which gave access to the walled village. Built in the first decade of the 16th century by order of D. Manuel for the Town Hall, it was also a prison, a bread and flour market, a library and is now a cultural space. The building fits, stylistically and spatially, in the Gothic tradition.
The current building replaced the original building, located in the square where the Mother Church is located today. With the expansion of the city from the second half of the 15th century, the political and cultural center of the city was progressively transferred to the west, occupying the Campo do Forno land. Construction began in 1505, outside the walls, and it is likely that by 1510 it was already completed.

Source: http://www.monumentos.gov.pt/site/app_pagesuser/sipa.aspx?id=3487