The Aqua Marcia aqueduct

The story

A river that walked on arches

If you go to Rome and walk along the Appia Antica or look to the east, you see long rows of stone arches crossing the countryside and reaching the city. They are the remains of the aqueducts, the great conduits with which the Romans brought water from distant springs. The Aqua Marcia was the third aqueduct of Rome, and for centuries it was considered the most precious.

It was built in the middle of the 2nd century BC, in 144 BC (the work lasted until 140). The job was entrusted to a magistrate, the praetor Quintus Marcius Rex, to whom the aqueduct's name remains tied: his term of office should have expired, but it was extended precisely to allow him to finish the work.

Why new water was needed

In the 2nd century BC Rome was already a big city, with many people living near the centre. The existing aqueducts were no longer enough, and so the Senate decided to build a new one.

Curiously, the work had been decided as early as 179 BC, but it stood still for years. The reason, according to the tradition, was the veto of a politician, Marcus Licinius Crassus, who did not want the pipes to cross his land. It was only many years later, in 144 BC, that work could really begin.

How it worked

The water was collected in the upper basin of the Aniene, a river that comes down from the Apennine mountains and flows into the Tiber in Rome. The main spring, which still exists, is near Marano Equo, between Arsoli and Agosta. The Greek writer Strabo, however, said that the water came from Lake Fucinus. From the spring to Rome, the aqueduct was about 91 kilometres long: for the Romans 61 miles and 710 paces, that is, a little over 91 kilometres.

For the water to flow by itself, without pumps, a constant and very slight slope was needed: the water descended by gravity, little by little. Most of the route, about 80 kilometres, was underground, in channels dug into the earth. The channel was protected by soil, hardly visible and difficult to damage. Only about 11 kilometres ran above ground, on rows of arches. The arches of the Aqua Marcia were the first monumental arches built for an aqueduct of Rome.

Near the city the aqueduct ran for about 9 kilometres on arches beside the Via Latina, as far as a place called ad spem veterem, near what is today Porta Maggiore, where several aqueducts met. Then, following what would become the line of the Aurelian Walls, it crossed over the Via Tiburtina with an arch, later turned into the Porta Tiburtina. The water was distributed from a point near the Porta Collina.

How much water it carried

The flow of the Aqua Marcia was enormous. At the spring it came to 4,690 quinariae, a Roman unit of measurement: today it is calculated to have been about 194,000 cubic metres a day, that is, over 2,200 litres every second. Part of this water also fed other aqueducts: 92 quinariae went to the Aqua Tepula, 162 to the Anio Vetus. The same arches were reused later to carry the Aqua Tepula and the Aqua Julia too.

A water famous for its quality

The Roman writer Pliny the Elder called it the clearest of all waters, a gift made to the city by the gods. It was the Romans' favourite for drinking, because it was considered cool and healthy.

Maintenance and revivals

An aqueduct needs constant care. The Aqua Marcia was restored several times: by Agrippa in 33 BC, by Augustus between 11 and 4 BC (who almost doubled its flow with a new spring, the Aqua Augusta), by Titus in AD 79 and by Caracalla in AD 213, who increased its flow and built a branch, the Aqua Antoniniana, to supply his great baths. On the Porta Tiburtina you can still read today the inscriptions with which Augustus, Titus and Caracalla recorded these works. Other restorations came under Hadrian, Septimius Severus and Diocletian, and also at the beginning of the 5th century, shortly before its final abandonment.

Many centuries later, in the 19th century, Pope Pius IX brought the aqueduct back into use. The new work was inaugurated on 10 September 1870.