The city was fortified around 500 CE by order of Theoderic the Great, king of the Ostrogoths, and in 722 it was enlarged by the Lombard king Liutprand. An ally of Frederick Barbarossa in his war against the Lombardy communes, it took part in the destruction of Tortona in 1115, obtaining certain privileges in exchange. Around 1300 Castelnuovo became part of the Duchy of Milan.
In 1570 it changed name from Castelnuovo di Tortona to Castelnuovo Scrivia, and become a fief of the Marini family and, after their extinction in 1778, of the Centurione family.
The parish church, in Romanesque style, dates to the 12th century although restored in the 16th and 19th century. It has a portal with medieval lions sculptures, lunette and capitals executed in Frederick Barbarossa times. The interior, on a nave and two aisles, houses a 15th-century fresco with the Madonna of the Misericordia and four 11th-century capitals from the old pieve.
Palazzo Pretorio (castle of the Torriani and Bandello families) has an ogival portico, with mullined windows. The upper storey has 11th- and 16th-century frescoes. The castle has a 39 m-high crenellated tower.
Church of Sant'Ignazio (17th century)
Palazzo Centurione (17th century), in Genoese style. It houses the city museum