Known as Sezzè until 1916, the village lies on the right bank of the Bormida River in the Alessandria plain.

Of very ancient origins, it is believed that the first historical nucleus of the settlement was established in 109 BC as a post station along the newly built road connecting Piacenza to Albenga, passing through Tortona, Acqui Terme, and Vado Ligure.

This road, commissioned by the censor Marcus Aemilius Scaurus, is known as the Via Aemilia Scauri.

The village is considered the birthplace of Aleramo of Monferrato, born in 934, founder of the eponymous territory, as noted on the sign at the entrance to the town. Here is also located the Aleramic Research Center, which includes the Aleramic Library. Witness to numerous historical events, the town had already functioned as a commune by the 13th century, with a mayor and two consuls. After changing hands several times, in 1707 it passed to the Visconti of the Duchy of Milan, and following the Battle of Marengo in 1800, it came under French rule. In 1814, Victor Emmanuel returned to rule Piedmont.

One of the most important monuments of Romanesque art is located here: the Church of Santa Giustina, founded in 772 by the Lombard King Liutprand and Queen Theodolinda. It became a Benedictine abbey in the 11th century, noted for its austere architectural style. The interior, with three spacious naves, features frescoes from the 14th and 15th centuries, as well as an ancient crypt from the original period, delicately divided by slender columns.

The Church of Santo Stefano, also known as Santa Maria di Banno after the adjacent ancient monastery, is very old but unfortunately not in good condition. Dating to the 12th century, it preserves heavily restored and damaged frescoes from the 14th, 15th, and 16th centuries.
Another notable building is the parish church, which appears monumental. Built in 1897 to a design by the engineer Giuseppe Gualandi, one of the leading figures of Italian Neo-Gothic architecture, it is an impressive example of the style.