The itinerary we propose traces the course of the River Olona from south to north, passing through the heart of the Province of Varese.
We start out from Castellanza and during its first part it crosses a densely urbanized zone, one of considerable economic importance due to its concentration of an important part of the companies to be found in the Province.
It is for this reason that we propose bicyclers who want to follow this route to only take on the most northern part where the road traffic is less intense.
The River Olona has its source to the north of Varese, on the slopes of the Campo dei Fiori in the locality of Rasa, to then flow into the River Po at San Zenone after a journey of 120 kilometres.
The old fluvial route of connecting Milan, Chur and Constance was to be found in its middle tract, comprised between Nerviano (Milan) and the Castle of Belforte (Varese),  to then pass on by Frascarolo, Ganna and Ponte Tresa and continue towards the Alpine passes of the Little St. Bernard, Lucomagno or St. Gothard.
Starting from the VI century, along the course of the River Olona, one had the development of the Seprio civilization, testified to both by the ruins of Castelseprio and the monastery of Torba.
Following the decline of Castelseprio's military power during the late XIII century, about 500 years later - beginning at the end of the eighteenth century and, indeed, up until the present day - the Olona Valley witnessed the birth of industrialization nella in the Province of Varese, a privileged place of Lombard economic development.
From Castellanza, onwards, along the whole of the river we can still see numerous examples of this.