Aveiro, located 75 kilometres south of Porto, is known as the 'Venice of Portugal' due to its canals, barcos moliceiros (gondola-like boats traditionally used for collecting seaweed) and arched bridges. The town has also played an important role in Portugal's salt industry.
When in Aveiro you should try the town's famous sweet Ovos Moles de Aveiro, which I wrote about in a story for Good Food Australia titled '10 things to eat and drink in Portugal'.
Make sure you also swing by Praia da Costa Nova while you're in the area to see the colourful houses along the beach.