Aveiro is a city and a municipality in Portugal. In 2011, the population was 78,450, in an area of 197.58 square kilometres (76.29 sq mi): it is the second most populous city in the Centro Region of Portugal (after Coimbra). Along with the neighbouring city of Ílhavo, Aveiro is part of an urban agglomeration that includes 120,000 inhabitants, making it one of the most important populated regions by density in the North Region, and primary centre of the Intermunicipal Community of Aveiro and Baixo Vouga. Administratively, the president of the municipal government is José Ribau Esteves, elected by coalition between the Social Democratic Party and the Democratic Social Centre, who governs the ten civil parishes (Portuguese: freguesias).

Located on the shore of the Atlantic Ocean, Aveiro is an industrial city with an important seaport.

The seat of the municipality is the city of Aveiro, comprising the five urban parishes with about 73,003 inhabitants. The city of Aveiro is also the capital of the District of Aveiro, and the largest city in the Baixo Vouga intermunicipal community subregion.

Aveiro is known as "the Portuguese Venice", due to its system of canals and boats similar to the Italian city of Venice.