Roman streets beneath the capital

In central Sofia, the present city does not cover its earlier lives so much as pass through them. Fragments of ancient Serdica sit beneath the streets and public passages: Roman walls, a gate and the lines of a city that once stood on routes between the Danube, the Aegean and Constantinople. The remains share the modern centre with government buildings and busy city routes. Bulgaria often feels like this meeting of times and directions. Its story is not one layer replacing another, but a country repeatedly remade at the junction of mountain roads, empires and the Black Sea.[1][2]

Roman ruins of Serdica in the foreground, with Banya Bashi Mosque and modern Sofia behind
The ruins of Roman Serdica stand before Banya Bashi Mosque in central Sofia, with the modern city rising behind them. Photo: David Stanley / Wikimedia Commons · CC BY 2.0

Bulgaria lies in southeastern Europe, between the Danube border with Romania and the Black Sea in the north and east, and Greece and Türkiye to the south. Serbia and North Macedonia form its western neighbours. The Balkan Mountains run across the country, dividing the Danubian plain from the warmer Thracian lowlands. Farther south and west, Rila, Pirin and the Rhodope ranges lift the landscape into high valleys, forests and snow-bearing peaks. This is not a large country, but its relief makes it feel like several: river plain, mountain corridor, agricultural basin and coast.[3][4]

The mountains shape water as well as movement. The Danube traces much of Bulgaria’s northern edge; smaller rivers descend toward the Black Sea or south toward the Aegean. The main watershed follows high ridges, so a journey across the country also crosses between river systems and climates. The Black Sea coast opens Bulgaria toward port cities such as Varna and Burgas, while mountain passes have long joined the interior to neighbouring lands. Geography here is connective: the Balkans are a spine that divides valleys but also carries roads, trade and armies through them.[3][5]

Sofia makes a useful first stop because its layers remain visible. The Thracian Serdi gave the ancient settlement its early name; Rome developed Serdica as a regional centre, and later rulers left Byzantine, medieval Bulgarian and Ottoman traces. The city became the capital of the restored Bulgarian state in 1879. Today, Orthodox churches, mosques, synagogues and socialist-era buildings stand within the same urban frame as new offices, trams and apartment blocks. The city’s landmarks are not a tidy timeline; they are reminders that political changes often accumulated in the same streets.[2][6]