Records show that the first city walls in Padua were built in 1195, and that the first ring of walls around the old Roman centre of the city was completed in 1210.
As the city expanded that ring would give way to two others: one built during the period of the Commune/ Ezzelini, the other during the time of Carraresi rule. These walls would then, in the sixteenth century, be the bases for the city fortifications built by the Venetians. The Mill Bridge and City Gateway are some of the best-preserved remains of the first ring of city walls, which had a total of 19 gateways and openings. The name comes from the number of water mills in the river below: there were a total of 34 in the fourteenth century, 24 in the eighteenth century and the last ones would only be removed in 1883-84. A five-arch bridge, the structure is of Roman origin and dates back to 40-30 B.C. However, it subsequently underwent various rebuilding work, some of which made used of the existing materials. An ogive archway, the Porta Molino itself is surmounted by a bulky tower. It is said that it was from the top of this tower that Galileo first saw the four satellites of Jupiter, an event that is recorded in a plaque with words by the epigraphist Carlo Leoni ( 1812-1874): “from this tower, Galileo revealed many of the pathways of the heavens”.
Porta Molino stands at the beginning of Riviera dei Mugnai [Millers Embankment], where you can see sections of the medieval walls partially incorporated into later houses. The neighbourhood around Via Dante – itself the old Roman road that ran up to the Gateway – was in the Middle Ages known for its numerous cobblers and shoemakers. The poorest of these, unable to afford a workshop in the city, moved out along the course of the river; even nowadays the Riviera del Brenta, which runs from Padua towards Venice, is home to a flourishing footwear industry.