As it was the last of the ten "gates" or communities to join the consortium of builders, it was named “Porta-Nova” (“New Gate”), replacing its earlier names of Silva Urbæ and Rondinella.The origins of Portanova date back to the 10th century. The "Tower of Portanova" is the remaining part of a castle built by the Dal Pozzo family in the 16th century, when they extended their Retorto fiefdom to include this area and established their summer residence there. The tower walls still show sections built using construction techniques typical of the barbarian era.The Orba stream, which borders the territory, has long been a source of concern due to erosion and flooding. However, this very proximity enabled the transformation of what was once a wooded area rich in wildlife into fertile farmland.Until 1929, Portanova was a suburb of Alessandria. It later became a hamlet of Casal Cermelli.It once had its own parish church, several rural chapels, and a primary school.