Gropello Cairoli is a comune (municipality) with a population of 4,235 in the Province of Pavia in the Italian region of Lombardy. It is located in eastern Lomellina, a short distance from the edge of the terrace that overlooks the Ticino river's floodplain, about 35 km (22 mi) southwest of Milan and about 15 km (9.3 mi) west of Pavia.

The town of Gropello Cairoli, which gained city status due to historical merit, is mainly centered around the former state road 596 (known as the Cairoli road) leading to Pavia, a route heavily trafficked, especially due to the presence of the A7 highway exit. The town is one of the few examples in Europe of a medieval strassendorf (a village developed along a road). In 2000, a bypass was inaugurated to divert traffic away from the town center.

A notable feature of Gropello Cairoli is the presence of two churches, San Rocco and the parish church dedicated to San Giorgio, which mark the main road from east to west.

The town most likely owes its name to the Latin Ripellium, due to its location on the banks of the Ticino River, or to Gruppellum, meaning a small cluster of houses.

Known since the 9th century, it was a fiscal curtis (estate) that King Berengar I granted in 900 to his loyal follower Folcuino, called Vasingone. It was possibly already defended by a castle at that time. In the following century, its lords were Bernardo (Count of Parma and, from 996, of Pavia) and his wife Rolinda (the illegitimate daughter of King Hugh). After regaining the estate from Emperor Otto II following a confiscation, they donated it to the canonry of the Holy Trinity in Pavia, which they had founded. It likely belonged to the domains of Pavia even before the city annexed the territories (Lomellina) in the 12th century after defeating the Palatine Counts of Lomello; within these domains, Gropello was included in the Lomellina district. After the Peace of Constance in 1183, it fell under the lordship of the Beccaria family, one branch of which took its name from this town. In 1437, Pietro Visconti, of a secondary branch of the illustrious family, was invested with the lordship as an inheritance from his mother, Orietta Beccaria.

The Visconti family of Breme and Gropello, divided into several branches, held the co-lordship of the fiefdom in the following centuries (which also included Zerbolò and Carbonara al Ticino). The fiefdom was inherited, at least in part, by the Lonati Visconti family and then passed by marriage to Count Lorenzo Taverna. After the end of feudalism (1797), the Taverna family remained the owners of the castle and a vast estate, which they sold in 1845 to the Pavia-born surgeon and university professor Carlo Cairoli.

Following the law of October 23, 1859, the town was included in the mandamento V of Garlasco and the III district of Lomellina, province of Pavia. The town, originally named Gropello, adopted the name Gropello Lomellino (Royal Decree of March 15, 1863, no. 1211) in 1863; later, in 1888, it took on its current name in honor of the five Cairoli brothers, heroes of the Italian Risorgimento and sons of Carlo Cairoli.

A close friend of one of the brothers, Benedetto Cairoli, was another distinguished citizen of Gropello, the philosopher Carlo Cantoni, a scholar of Kant (who was awarded a posthumous honorary degree by the University of Königsberg for his studies on Kant) and a senator of the Kingdom of Italy from 1898. He was responsible for the construction of the railway. The house where he was born is still intact and now hosts a guesthouse on the upper floors, while the frescoed rooms on the ground floor and the century-old park are reserved for events and receptions.