Symbol of Italy's economic and industrial miracle and mass motorization, the Autostrada del Sole turned 60 years old. The Autosole is still the largest public work ever built in Italy and the longest highway in operation: to build it, engineers went to the United States to study the construction systems of major highways. With construction sites not yet completed, many of the designs for the A1 viaducts were displayed at MoMA in New York, in the 1964 exhibition devoted to 20th-century engineering. The laying of the foundation stone, in San Donato Milanese, took place on May 19, 1956, under the eyes of then-President of the Republic Giovanni Gronchi. Eight years and four months later, on October 4, 1964, the work was inaugurated by then Prime Minister Aldo Moro. In just 3,060 days, 755 kilometers of road, 400 bridges and viaducts, 38 tunnels, 57 slip roads and 56 service areas were built. As a result, Milan and Naples were finally connected. The North and South of the country were touching for the first time.