Autostrada A4 (Italy)

The Autostrada A4, or Autostrada Serenissima ("Serenissima motorway"), is an autostrada (Italian for "motorway") 523.1 kilometres (325.0 mi) long in Italy located in the regions of Piedmont, Lombardy, Veneto and Friuli-Venezia Giulia which connects Turin and Trieste via Milan and Venice crossing the entire Po Valley from west to east.

The city of Venice (or rather, Mestre, a mainland frazione of Venice) originally formed a bottleneck on the A4, but is now bypassed by the Passante di Mestre (the old route through Mestre was renumbered A57). The A4 passes just north of the city of Milan, where it is toll-free. It is a part of the E55, E64 and E70 European routes.