Along with the roads, the aqueducts were the great engineering works with which the Romans amazed the world. From 312 BC they built eleven aqueducts to feed palaces, fountains and spas.
Many of them followed a similar path, more or less long, from the Aniene Valley, above Tivoli, crossing Prenestina and Casilina, skirting via Latina and via Appia, entering the city from Porta Maggiore.
Porta Maggiore in fact was not a door but an Arch of Triumph built between 38 and 52 after Christ, then 220 years before becoming the main gate of the Aurelian Walls, to allow the Claudio and Anio Novus aqueducts to pass over the Prenestina streets (to Praeneste) and the Labicana to route to Labico.
Nerone poi fece fare partire da Porta Maggiore l'acquedotto che alimentava la Domus Aurea, passando per San Giovanni.
Nero then had the aqueduct that fed the Domus Aurea go from Porta Maggiore, passing through San Giovanni.
Porta Tiburtina also became a door later, before it was an Arch to cross over the road.
Whereas the Arco di Dolabella is the opposite case.
First it was a gate of the ancient Servian Walls and then it became an arch to allow the Neronian aqueduct to pass over the road.
The aqueducts fed the imperial palaces and the great spas, but to travel 80 km with a constant slope, bringing up to 3000 litres per second, it would not have been easy even with modern technologies and yet they succeeded.
Two aqueducts meanwhile came from the north, from the Bracciano area, along the Via Aurelia to feed the Janiculum and the Vatican.
The aqueduct of Acqua Vergine finished in 19 BC meanwhile has everything underground. It started from Collatina but entered from the north via Villa Ada, Parioli and Pincio.
It has been restored several times and fed the Trevi Fountain, the Barcaccia and Piazza Navona. The conduits went to "via Condotti".
The last ancient aqueduct was the Acqua Alexandrina, made by Alessandro Severo in 226 AD, and gave its name to the Alexandrine Quarter.
Around 530 during the Gothic war the aqueducts were interrupted and did not work for 1000 years, except in part that of the Acqua Virgo which continued to be active.
Then in 1585 Pope Sixtus V had the Acqua Felice repaired, restoring various sections of the Acqua Marcia and Acqua Claudia aqueducts, from the village of Colonna to the Moses fountain, passing through Porta Furba, Porta Maggiore and Porta Tiburtina.
In 1605 Paul V had the Acqua Paola rebuilt, restoring the line from Bracciano to the Fontanone del Gianicolo.
But Paola water was not as good, arousing the irony of the Romans, who said "it is as good as paola water" indicating something of little value.
To conclude this story, it must be remembered that the last Pope King, Pius IX, had the Acqua Marcia restored, bringing water to Piazza Esedra, with the inauguration in 1870, just 9 days before the take off of water at Porta Pia.
The beautiful Fountain of the Naiads in Piazza Esedra was made 30 years later.
A stretch of the Acqua Vergine has been visible since 2017, found under the Rinascente of via del Tritone.