Aqua Marcia
In 144 BC, the Roman Senate authorized a new aqueduct to replace two aging systems that had become dilapidated. The Aqua Appia and Aqua Anio Vetus suffered from illegal diversions by private citizens who stole water for their own use. Censor Cato the Elder passed laws in 184 BC to remove these unauthorized pipes but flow rates remained too low for Rome's growing population. Praetor Quintus Marcius Rex received judicial authority extended specifically to complete this massive project. He was an ancestor of Julius Caesar and oversaw construction funded by spoils from Corinth's destruction in 146 BC. Traditionalists opposed bringing water to the Capitoline Hill due to warnings in the Sibylline Books about such passages. The Senate rejected their objections in 140 BC when the case reached them. This decision marked the first time an aqueduct entered Rome on monumental arches rather than following contour lines underground.
Agrippa repaired the aqueduct for the first time in 33 BC before Augustus undertook a major rebuild between 11 and 4 BC. A report from consuls Quintus Aelius Tubero and Paullus Fabius Maximus prompted this extensive restoration effort. Augustus added an additional source called Augusta located 800 roman paces away from the original spring. An inscription commemorating his work still spans the Via Tiburtina today, later integrated into the Aurelian Wall. By Nero's reign, private citizens had siphoned off much of the supply leaving only a trickle flowing through the city. Trajan completely rebuilt the branch serving the Caelian Hill and Aventine Hill during his rule. His successor Hadrian restored various parts of the system while Septimius and Caracalla jointly commissioned further work in 196 AD. Caracalla added another water source specifically to supply baths he constructed during his sole rule. Diocletian likely commissioned restorations after building his famous baths, with final work occurring under Arcadius and Honorius.
The ancient source sat near small lakes formed by two springs in the Anio valley between modern towns of Arsoli and Marano Equo. This location east of Rome also supplied other aqueducts including Aqua Claudia and Aqua Anio Novus. The first 80 kilometers ran underground before emerging on large monumental arches to maintain proper water pressure. The initial stretch followed the right bank of river Anio crossing it just before Vicovaro. It joined routes with Aqua Anio Vetus at lower altitudes then continued toward Tivoli. After bypassing Tiburtini Mountains and passing Gericomio municipality, the line crossed Gallicano area via Praenestina road. Alternating bridges and underground sections characterized this long journey through Lazio terrain. From Capannelle area the route headed directly toward Rome surfacing at the seventh mile of Via Latina. A limaria pool or settling basin existed there before approximately 9 kilometers of arches flanked Via Latina. These structures reached Rome's locality ad spem veterem near Porta Maggiore where multiple aqueducts converged.
Ponte San Pietro features an enormous central arch spanning 16 meters over the Mola stream. Originally constructed from local porous calcareous stone ashlars, its abutments measured 3.84 meters wide at base narrowing to 2.77 meters. The north-west side likely included a smaller arch while three small arches occupied the south-east end. Reinforcement under Titus or Hadrian covered the entire structure in cement rebuilding the south-east end completely. Ponte Lupo stands more than 30 meters high and stretches over 80 meters long across deep Aniene Valley. Built in 144 BC it allowed water to cross the valley on its way to Rome with a road running along its top. This bridge sits on private estate of San Giovanni in Campo Orazio today. Ponte Caipoli originally carried the aqueduct on single large arch from 144 BC replaced later by double brick arch reaching 13 meters height. Numerous restorations remain clearly visible on its abutments and vault throughout following centuries. Between Ponte Caipoli and Ponte della Bullica lies tunnel dug into tuff about 1.2 meters wide extending 200 meters.
Frontinus measured Aqua Marcia flow at its source around AD 97 recording 4690 quinariae total volume. This made it the second-greatest water source supplying the city after only one other system. Modern estimates for one quinaria vary widely ranging from specific cubic measurements to different daily volumes. These variations create calculated daily flows between approximately 150,000 and 200,000 cubic meters per day depending on conversion methods used. The branch serving Caelian Hill and Aventine Hill received complete rebuilding during Trajan's rule increasing capacity significantly. Later emperors augmented supply systems when private citizens siphoned off portions for personal use. Augustus linked additional sources called Augusta located 800 roman paces away from original spring point. This expansion helped maintain adequate pressure through long underground sections before emerging onto monumental arches near Rome. The aqueduct remained functional enough that modern Acqua Felice runs along stretches of its ancient route since 1586.
The still-functioning Acqua Felice from 1586 follows long stretches along the original Aqua Marcia route today. This modern system utilizes the same source springs near Arsoli and Marano Equo that supplied ancient Rome. The general locale east of Rome served multiple aqueducts including Anio Vetus, Anio Novus, and Aqua Claudia throughout history. Roman engineering techniques demonstrated in surviving bridges like Ponte della Bullica influenced subsequent infrastructure projects across Italy. The bridge crosses Collafri stream with single round arch constructed from radial tuff ashlars measuring 5.8 meters span. It stands 5.5 meters high and 3.3 meters wide spanning 10.6 meters total length without radical restorations. Service tunnels about 230 meters long run alongside every 30 to 40 meters featuring vertical inspection shafts for maintenance access. These putei allowed easier extraction of material using wagons crossing Collafri hill while keeping shafts shorter than surface alternatives. The main branch covered two-thirds of ancient city reaching Quirinal then Capitol while secondary rivus Herculaneus served Caelian and Aventine hills.
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Common questions
When was the Aqua Marcia aqueduct built and authorized by the Roman Senate?
The Roman Senate authorized the construction of the Aqua Marcia in 144 BC. The project concluded when the Senate rejected traditionalist objections to bringing water to the Capitoline Hill on the 2nd of May 140 BC.
Who funded the construction of the Aqua Marcia and what was their relationship to Julius Caesar?
Praetor Quintus Marcius Rex oversaw the construction of the Aqua Marcia using funds from spoils taken during the destruction of Corinth in 146 BC. He was an ancestor of Julius Caesar and received judicial authority specifically to complete this massive infrastructure project.
Where is the source of the Aqua Marcia located relative to modern towns?
The ancient source sat near small lakes formed by two springs in the Anio valley between the modern towns of Arsoli and Marano Equo. This location east of Rome also supplied other aqueducts including Aqua Claudia and Aqua Anio Novus.
What are the dimensions of Ponte Lupo and where does it stand today?
Ponte Lupo stands more than 30 meters high and stretches over 80 meters long across the deep Aniene Valley. It sits on a private estate of San Giovanni in Campo Orazio today after being built in 144 BC.
How much water did Frontinus measure flowing through the Aqua Marcia at its source around AD 97?
Frontinus measured the Aqua Marcia flow at its source around AD 97 recording 4690 quinariae total volume. Modern estimates for one quinaria vary widely ranging from specific cubic measurements to different daily volumes creating calculated flows between approximately 150,000 and 200,000 cubic meters per day.