The long-lasting Roman bridges

Ancient Roman Bridges still standing

Roman bridges have survived for centuries, while most modern bridges need replacing about every 70 years. Early Romans certainly didn’t invent bridges, but they did more to perfect and refine large bridge engineering than any civilization thus far. In fact, a 1990s survey conducted by Italian scholar Vittorio Galliazzo documented 931 surviving (whole or partial) Roman bridges in 26 countries, all once a part of the vast Roman Empire. 

Ponte Fabricio from 62AD crosses the Tiber

Roman emperors were under a lot of pressure to enlarge the Empire during their reign. Expanding roadways was a great tool for conquering while facilitating trade and commerce. Since most roads were planned in a straight line, that required enormous collateral projects. Swamps had to be drained, bridges raised to span valleys and huge amounts of rock and dirt had to be removed. Borrowing on Greek knowledge, along with their own accrued skills for large scale construction, they formulated revolutionary techniques of which the results are still seen, and used, today. 

The arch was the Romans’ most important development in architecture. Roman arch design featured stone butted against stone, in an angled fashion to create tensile strength. This, in turn, produced a steady pressure able to support a tremendous load. The hollow of the arch also lessened the weight of the structure, as well as allowing passage for water flow and vessels. Bridge construction also incorporated concrete, developed by the Romans: a mixture of lime, pozzolana (a volcanic ash), and water with the addition of aggregate. The volcanic ash concrete also held up well under water, allowing Roman-built pilings to continue doing their job to this day. 

Ponte Rotto

Spanning the Tiber in Rome, the ancient Ponte Rotto (broken bridge) from 142 BC was the first bridge built using stone arches. Roman bridges such as Rome’s Ponte Fabricio, built in 62 AD, are still in use today. Ponte Fabricio joins Isola Tiberina to the main part of Rome and is used for foot traffic only. Ponte Sant’Angelo from 134 AD spans the river and leads across to the Castel Sant’Angelo, Hadrian’s mausoleum. 

Ponte Sisto was built in 1475 by Pope Sixtus IV called the “papa tosto” or hard-headed pope by the Romans. The occasion was the Jubilee and the bridge was financed in part by taxes levied on courtesans, a business booming in Renaissance Rome. The rationale was to facilitate moving pilgrims from the left bank where most of the city was, including the seven hills, to the Vatican on the right bank. It is thought that this bridge replaced an old wooden bridge built by Vipsanio Agrippa in 12 BC, rebuilt and restored over the years. An inscription at the end of the bridge toward the city reads: “You who pass here thanks to Sixtus IV, pray God that he will live long and enjoy the best of health.” It continues that he had it redone “at his own expense and attention” and wished it to be renamed after him – the Sisto Bridge. 

Some bridges built with this technology are still functional, not only in Rome and other Italian cities but in many parts of the ancient Roman Empire. Ponte Pietra (‘Stone bridge’), was built in 100 BC over the Adige river in the historic center of Verona, Italy. Several examples in Spain are in good condition. The famous Alcantara bridge, 600 feet long with six arches 148 feet high. The architect of the latter in 105 AD left an inscription that is still visible that says “I built a bridge that will last for centuries.” And so it did. 

The Alcantara Bridge

The Puente Romano (‘Roman bridge’) over the Guadiana River at Mérida in southwest Spain is the world’s longest surviving bridge from ancient times. Sixty spans of the original sixty-two, for a total of 721m instead of the original 755m, remain. Completed in 117 AD during the reign of Trajan, it is still in use and it was recently made available for pedestrians only. Only after the eighteenth century, with the Industrial Revolution and the production of steel, was the stone arch surpassed with the use of new materials and technical advances.