It is also part of the geographic area named Gera d'Adda [it], included among the rivers Fosso Bergamasco to the North, Adda to the West and Serio to the East.

During the conquest of the Cisalpine Gaul (Gallia Cisalpina) by the Romans, a castrum was built to guard an important trading crossway and the surrounding villages.

Treviglio was founded in the Early Middle Ages as a fortified town, unifying three preexisting settlements: Cusarola (Celtic), Pisignano (Roman) and Portoli (Lombard).

The first official document found citing the new town dates back to November 964 D.C. Around the year 1000, Treviglio offered refuge to the inhabitants of Oriano, a commune near Brescia, which had been destroyed in the course of the struggle between Arduin of Ivrea and Henry II who were warring for the Imperial crown.

In 1167, Treviglio joined the first Lombard League, which had the aim of preserving local jurisdiction and droit de régale, a purpose that was achieved with the victory over emperor Frederick I 'Barbarossa', at the Battle of Legnano.

It describes a government held by sixty Consuls - initially twenty each for everyone of the original ethnic communities, thereafter fifteen for each district - remaining in office for six months.

In 1395, Treviglio gained formal autonomy from the Holy ROman Empire, which it held as a "Separate Land of the Duchy of Milan", except for several brief Venetian occupations (1431-1433; 1448–1453 and 1499–1509).

On 28 February 1522 General Odet de Foix Viscount of Lautrec, leading the French army through Northern Italy on its way to the South, came to punish the town for its insolence.

Thus, they marched barefoot, each one wearing a rope at the neck, and approached the General, offering the keys of the city and their lives in order to spare the population.

Finally, when the French troops entered the town without encountering resistance, a fresco of Our Lady, in front of which the inhabitants were praying, appeared to weep.

Warned of this portentous event, the General checked the building and its walls to verify the veracity of the miracle and, finally persuaded, deposed helmet and sword at the feet of the fresco and left the city.

After many long years of war, the French sold Treviglio to the Spaniards, albeit the town was formally still under the aegis of the Holy Roman Empire.

On 17 December 1915 Benito Mussolini married in civil union Rachele Guidi in Treviglio, after the future Duce had recovered in the local hospital.

With a Presidential Decree of 8 January 1960, Treviglio was declared a City, as promised by King Victor Emanuel II in 1860, due to its historical involvement in the achievement of the Italian Independence.

There are also schools of mountain climbing, cycling, BMX, motorcycle, horse riding, diving, water polo, swimming, pilates, martial arts, artistic gymnastics and modern and classic dance.