Diocletian’s Aqueduct: The Emperor’s Hidden Masterpiece
Split’s UNESCO-protected Diocletian’s Palace is the beating heart of this coastal city, its ancient stones echoing tales of Roman grandeur and Mediterranean life. But beyond the palace walls lies an equally remarkable and often overlooked relic of Emperor Diocletian's reign: the aqueduct. Stretching nearly 9 kilometers, this engineering marvel once carried fresh water from the Jadro River to both the imperial residence in Spalato (modern Split) and the bustling Roman city of Salona (present-day Solin).
This aqueduct isn’t just a relic—it’s a testament to Roman ingenuity, capable of delivering enough water to serve a city of over 170,000 people by modern standards. While the palace may steal the show, the aqueduct deserves its own applause. So why not give it the spotlight it deserves on your next visit to Split?
The Visionary Behind the Waterworks
Diocletian was no ordinary emperor. Born in Salona (modern Solin), he worked his way to the highest position in the empire and later became the only Roman emperor to voluntarily abdicate power. When he stepped down in 305 CE, he chose to retire to his luxurious palace on the Dalmatian coast. But what’s a palace without a steady water supply?
Diocletian ordered his architects to create a state-of-the-art aqueduct to carry water from the Jadro River—a spring so pure that even today, it supplies Split’s drinking water. The aqueduct was built with precision, with a slope so gentle (just 0.37%) that water flowed seamlessly across valleys, underground tunnels, and arched bridges to reach the palace.
Legend has it that Diocletian himself oversaw some of the construction, demanding perfection from his engineers. While this might be an embellishment, it’s easy to imagine the emperor taking a personal interest in this lifeline for his palace and the workshops within.
A Triumph of Roman Engineering
The aqueduct’s design was a masterpiece of both functionality and beauty. Built with durable stone blocks, its above-ground sections featured soaring arches that cut through the landscape, particularly in the area now known as Bilice. Where the terrain demanded, the aqueduct dipped underground, with some tunnels reaching depths of 21 meters.
Archaeologists marvel at how efficiently the aqueduct was constructed. Diocletian’s architects achieved a perfect balance of minimal excavation and maximum durability, showcasing an extraordinary level of engineering skill. The aqueduct was built to last, and though damaged during the 6th-century Gothic invasions, large sections remained intact for centuries. One of the few certainties about the large expanse of buildings (Aspalathos) in Diocletian’s day is that it contained textile works, as the office of textile works manager, ‘Procurator gynaecii Iovensis Dalmatiae - Aspalato’, is listed in ‘Notitia Dignitatum’, a comprehensive document listing Roman officials and their administrative offices up to the late 4th and 5th centuries. Textile production was extremely profitable, and Diocletian made the whole purple dyeing industry a state monopoly. There were numerous textile production and cloth dyeing facilities around the Empire, including at Salona. A lot of water was needed in textile production. Aspalathos was close to a river, which, together with the extended aqueduct, meant that water was plentiful. Sulphur was used in the bleaching process, and Aspalathos had sulphur springs, near the present-day fish market. These might have been among the reasons for Diocletian choosing Aspalathos for his Palace.
A Second Chance
Fast-forward to the 19th century, when the Austrian Empire ruled over Dalmatia. Recognizing the aqueduct’s importance, they undertook a major restoration project in 1855, led by the Croatian architect Vicko Andrić. By 1879, 28 monumental arches in Dujmovača had been rebuilt, and the aqueduct was functional once more, delivering water to Split for decades.
The 20th century saw modern technology gradually replace the aqueduct’s role as Split’s water supplier. By 1932, a pump station in Kopilica had taken over, and by 1948, the aqueduct was retired altogether. Today, it stands as a historical monument, with the restored arches in Bilice being its most iconic feature.
Tales of the Jadro River
The Jadro River, the aqueduct’s source, has a story of its own. Constantine Porphyrogenitus, a 10th-century Byzantine emperor and chronicler, claimed its water was “the best tasting of all.” Perhaps it’s no coincidence that Diocletian chose such a pristine source for his palace. Locals say the river’s waters still carry the blessings of the Roman gods—though that might just be an excuse to boast about their city’s excellent tap water!
Exploring the Aqueduct Today
While the Diocletian Palace rightly draws millions of visitors each year, the aqueduct offers a quieter, off-the-beaten-path glimpse into Roman history. The most photogenic section lies in Bilice, just south of Solin, where 17 arches rise majestically over the landscape. Nearby, you can explore parts of the aqueduct that dive underground, giving you a sense of its scale and complexity.
For history buffs, a walk along these ancient stones is like stepping back in time. Picture the water flowing steadily from the Jadro River, bringing life to the emperor’s palace and the villages along the way. And while you’re there, imagine the Gothic invasions that left the aqueduct in ruins or the Austrian architects who lovingly restored it centuries later.
Why Visit Both the Palace and the Aqueduct?
Diocletian’s Palace may be the centerpiece of Split, but the aqueduct is its lifeline—a testament to the emperor’s vision and the brilliance of Roman engineering. Visiting the palace without seeing the aqueduct is like reading half a book; you miss the full story.
Take a moment to appreciate the ingenuity that brought fresh water to this ancient city. Whether you’re admiring the restored arches in Bilice, exploring underground tunnels, or simply pondering the flow of history, the aqueduct offers a perspective on Split that’s as refreshing as the waters it once carried.
Don’t Miss the Full Experience:When planning your trip to Split, carve out time to explore both Diocletian’s Palace and the aqueduct. Together, they paint a vivid picture of Roman life, ingenuity, and the legacy of an emperor who left an indelible mark on Croatia’s Dalmatian coast.
Check out this video on the aqueduct’s construction and restoration to get a sense of the engineering brilliance behind it!
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