Ancient Serdica

In most cities, history sits behind glass, preserved, labelled and carefully separated from modern life. In Sofia, it lies beneath your feet.

Step into the Ancient Serdica Archaeological Complex and you are not simply observing the past, you are walking through it. Roman streets stretch out before you, fragments of homes and public buildings emerge from the ground, and the outline of an entire city begins to take shape beneath the rhythm of modern Sofia above.

This is not a reconstruction. It is the real foundation of the city. And it tells a story that begins nearly two thousand years ago, when Sofia was known not as Sofia, but as Serdica – one of the Roman Empire’s most prized settlements in the Balkans.

Thracian Foundations

Long before Roman legions marched into the region, the area around modern Sofia was inhabited by the Thracian tribe known as the Serdi.

They were drawn here for the same reason as every civilisation that followed: the mineral springs. These naturally heated waters provided both practical and spiritual value, shaping settlement patterns and establishing the area as a place of importance.

The name “Serdica” itself is believed to derive from this tribe, a reminder that even as empires came and went, traces of earlier cultures endured.

The Birth of Serdica

The Romans formally incorporated the region into their empire in the 1st century AD, and with them came a transformation that would define the city for centuries.

Serdica was laid out according to the principles of Roman urban planning. Streets intersected at right angles, forming a grid that organised both movement and space. Public buildings – basilicas, baths, forums – were constructed with precision and purpose, reflecting the order and ambition of Rome itself.

Fortified walls enclosed the city, protecting its inhabitants while also marking its importance within the empire. Serdica was not a minor outpost; it was a thriving administrative and commercial centre.

And, crucially, it was a city that mattered to emperors.

Constantine’s City

Few endorsements in history carry as much weight as that of Constantine the Great.

According to historical accounts, Constantine is said to have declared, “Serdica is my Rome,” a statement that speaks volumes about the city’s significance in the 4th century.

At a time when the Roman Empire was undergoing profound change, including the rise of Christianity, Serdica emerged as a key location. It hosted important councils and served as a strategic hub between East and West.

Walking through the ruins today, it is not difficult to imagine why. The city’s position, resources and infrastructure made it both practical and desirable, a place where power could be exercised and maintained.

Life in Roman Serdica

The ruins you see today offer glimpses into daily life in ancient Serdica.

Stone-paved streets – once bustling with traders, soldiers and citizens – remain remarkably intact. You can trace the lines of residential buildings, public spaces and administrative structures, each revealing something about how the city functioned.

Roman life was highly organised. Water systems, drainage and heating technologies were integrated into buildings, reflecting an advanced understanding of engineering. The nearby thermal springs fed bathhouses, continuing a tradition that had begun long before Rome and would continue long after.

Markets would have filled the air with noise and activity, while public buildings served as centres of governance and social interaction. This was not just a place to live, it was a place to participate in the life of the empire.

Decline and Transformation

Like all Roman cities, Serdica eventually faced decline.

As the Western Roman Empire weakened and external pressures increased, the city’s fortunes shifted. Invasions, political instability and economic changes altered its role within the region.

Yet Serdica was never entirely abandoned.

Instead, it evolved.

Under Byzantine rule, the city retained its importance, adapting to new political and religious realities. Christianity became more prominent and existing structures were repurposed or rebuilt to reflect changing needs.

Later, during the medieval Bulgarian period, the city (then known as Sredets) continued to develop, building upon its Roman foundations even as new layers were added.

Buried Beneath Time

Over the centuries, the physical remains of Serdica gradually disappeared from view.

New buildings rose above old ones. Streets were repaved, foundations were buried and the city expanded without always recognising what lay beneath. For generations, the Roman past of Sofia existed largely out of sight, hidden below the surface of everyday life.

It was only in the modern era, particularly during construction and infrastructure projects, that these ancient layers began to re-emerge.

What followed was a process of discovery that would reshape how Sofia understood its own history.

Rediscovery and Preservation

Archaeological excavations in the 20th and 21st centuries revealed the extent of Serdica’s remains.

Rather than removing or isolating these discoveries, Sofia chose a different approach, one that integrates the past into the present. The Ancient Serdica Archaeological Complex is a result of this vision.

Today, glass domes, modern walkways and open-air sections allow us to explore the ruins while protecting them from the elements. The site is seamlessly woven into the urban fabric, sitting alongside metro stations, government buildings and busy city streets.

This integration is what makes the experience so powerful.

We are not stepping away from the city to see its history, we are encountering that history as part of the city itself.

A City Within a City

As we walk through the complex, the layout of ancient Serdica begins to reveal itself.

We follow the lines of major streets, stand within the remains of buildings and imagine the scale of the city as it once was. Informational displays help contextualise what we are seeing, but much of the experience is intuitive.

The stones speak for themselves.

There is something uniquely compelling about standing on a Roman road while modern life continues just metres away. The sound of footsteps echoes differently here, as if carrying the weight of centuries.

It is a reminder that cities are not static, they are built, rebuilt and layered over time.

Serdica in the Context of Sofia

The Ancient Serdica ruins are not an isolated attraction, they are central to understanding Sofia as a whole.

Nearby, we explore landmarks from other periods of the city’s history, including the Banya Bashi Mosque, which reflects the Ottoman era and the Central Mineral Baths, which connects to both ancient and modern traditions of bathing culture.

Together, these sites create a layered narrative that defines Sofia’s identity. Each era has left its mark, but none has completely erased what came before.

Serdica remains the foundation, both literally and figuratively.

Walking Through Time

What sets the Ancient Serdica Archaeological Complex apart is the experience it offers.

This is not a museum in the traditional sense. There are no barriers separating us from the past, no prescribed route that dictates how we should move or what we should see.

Instead, we are free to wander.

To pause.

To imagine.

And to consider what it means to stand in a place where people have lived, worked and walked for nearly two millennia.

It is an experience that is as much about feeling as it is about learning.

Good to Know

The Ancient Serdica Archaeological Complex is located in the centre of Sofia and is easily accessible on foot. Many sections are open-air and free to explore, while some covered areas may have specific access points.

Wear comfortable shoes, as the surfaces can be uneven and take your time navigating the site. Early morning or quieter periods allow for a more reflective experience, while busier times bring a sense of how the space integrates with modern life.

The site is best visited as part of a broader walking tour, as many of Sofia’s key historical landmarks are within a short distance: Banya Bashi Mosque, Central Mineral Baths and the Rotunda of St. George.

The Ancient Serdica ruins are not just a highlight of Sofia, they are its foundation. They offer something that few cities can: a direct, tangible connection to the ancient world, experienced not in isolation, but as part of a living, evolving city.

And once you’ve walked those Roman streets, it’s hard not to feel connected to the city in a way that lingers long after you leave.

Would I Return?

Yes.