Cornfields, a power plant, the Danube flowing wide and calm: nothing, at first glance, suggests that you are docking above a Roman capital. Yet that is the very reason for the Kostolac port call, in eastern Serbia. Three kilometres from the river lie the ruins of Viminacium, a city that once governed an entire province of the Empire, and which archaeologists are unearthing shovel by shovel amid the crops. Lower Danube cruise ships, on their way to the Iron Gates, stop here precisely for it, and few passengers walk back up the gangway without having changed their minds about this corner of Serbia.

Viminacium, a Forgotten Capital

Founded in the 1st century as a legionary camp near the confluence of the Morava and the Danube, Viminacium became the capital of Upper Moesia, a first-rate military and trading stronghold on the Empire's frontier. Emperors stayed here, armies gathered here before northern campaigns, and the city even minted its own coins for a few decades. Unlike so many ancient sites covered by modern cities, it was never rebuilt: its streets, baths and necropolises lie waiting beneath the fields, making it an exceptional field of study that UNESCO has placed on its tentative World Heritage list.

Walking Through the Excavations

The visit is led by site guides, often archaeologists themselves, whose enthusiasm is contagious. Under large shelters, you walk through baths with underfloor-heated rooms, the remains of the military camp's gates, and a mausoleum where funerary frescoes have preserved faces painted seventeen centuries ago, including a very moving one of a young woman with a direct gaze. The explanations make the city surprisingly tangible: talk turns to legionaries' rations, aqueducts, gladiators and taxes, and the surrounding fields suddenly take on the outlines of streets and forums again. The contrast with the chimneys of the nearby power plant adds an unforgettable strangeness to the place. A modern visitor centre, with a café and shop, lets you catch your breath between excavation areas.

A Mammoth Among the Romans

In 2009, the nearby Drmno coal mine yielded an even older surprise: the remarkably complete skeleton of a female mammoth, uncovered from sediments dozens of metres below the surface. Named Vika, the animal now holds pride of place in a pavilion of the archaeological park, surrounded by partial remains of other giants found since in the same basin. Going in a few steps from Roman frescoes to a Pleistocene colossus gives the port call a dizzying depth of time that delights children and history buffs alike, and provides the best topic of conversation in the ship's lounge on the way back.

The Town and the River

Kostolac itself remains a mining town with no tourist pretensions, and that is also what gives the stop its flavour: the coaches pass through a rural, working-class Serbia that the great Danube capitals never show, vegetable gardens, tractors and plum orchards included. Depending on the program, the day is rounded out with a tasting of regional wines or local specialties, led by creamy kajmak and cured meats, served with easygoing hospitality. The heart of the visit, however, lies in following the guide's footsteps, between two excavation trenches, where Serbia tells the story of Rome.

When the boat sets off again toward the gorges or toward Belgrade, the chimneys fade behind the poplars on the bank. What stays with you is a face painted in a mausoleum, a mammoth tusk emerging from the coal, and the idea that the Danube here is not just a river: it is Europe's oldest frontier, and it has not finished giving up its secrets.