Sofia is the capital and largest city of Bulgaria, home to about 1.22 million people at the 2021 census. It lies in the west of the country in the Sofia Valley, a high basin at an average altitude of 550 m, at the northern foot of Vitosha mountain, which rises to 2,290 m within sight of the city centre. That makes Sofia the highest capital in the European Union after Madrid. Unlike most European capitals it has no great river. What it has instead are 49 mineral and thermal springs, and the hot water that still flows in the middle of town is the reason people settled on this spot some seven thousand years ago. Everything else about the city, from its Roman streets to its winter smog, follows from that basin, those springs and that mountain.
The Sofia Valley: A Basin 550 Metres Up
Stand anywhere in central Sofia and there are mountains on the horizon. The Sofia Valley, the largest of the eleven Sub-Balkan valleys, covers about 1,180 km² and stretches 75 km from north-west to south-east, while its width varies from 5 to 20 km. The main ridge of the Balkan Mountains closes it to the north. To the south-west rise Viskyar, Lyulin and Vitosha, and to the south the Lozen division of Sredna Gora. The city grew on the western side of this floor, just west of the Iskar River.
The Iskar is the valley's only real river, and it barely touches the city. It rises in Rila, Bulgaria's highest mountain, enters the valley near the village of German, runs north past the eastern suburbs and under the runways of Vasil Levski Sofia Airport, and leaves through the Iskar Gorge at Novi Iskar to cut across the Balkan range. Inside the city there are only shallow streams such as the Boyanska, Vladayska and Perlovska. The valley's importance came from the routes into it: three mountain passes lead to the basin, and they have carried the main roads since antiquity. That put Sofia near the centre of the Balkan Peninsula, on the natural line between Central Europe and Constantinople. For the wider peninsula it sits in, see our guide to the geography of the Balkan Peninsula.
Forty-Nine Springs and the Roman Town of Serdica
The springs came first. A Neolithic village at Slatina dates to the 5th or 6th millennium BC, and another settlement grew up in the 3rd or 4th millennium BC on the site of today's National Art Gallery, which has been the city's centre ever since. A tribe called the Serdi gave the town its ancient name, Serdica. Roman forces under Crassus campaigned here around 29 BC, and under Trajan (98–117) it became a municipium named Ulpia Serdica. It sat on the Via Militaris, the Roman road from Singidunum, modern Belgrade, to Byzantium, and served as the capital first of Dacia Aureliana and then of Dacia Mediterranea. The emperors Aurelian and Galerius were born here. In 311 Galerius issued his Edict of Toleration in Serdica, the first edict to legalise Christianity, two years before the Edict of Milan. Constantine the Great is quoted as saying "Serdica is my Rome," and he considered it as a capital before choosing Constantinople.
The Roman town is still under the modern one, roughly between the TZUM department store, the Sheraton hotel and the Presidency. Its oldest standing building, the red-brick Rotunda of St George, was built in the early 4th century as part of a Roman bath complex and later became a church; frescoes of 22 prophets, each over two metres tall, crown its dome. In 343 the Council of Serdica met in a church on the ground where the 6th-century Church of Saint Sofia was later raised. Excavations in the centre have since exposed much more: the eastern and western gates, stretches of the city walls, thermal baths and part of the Amphitheatre of Serdica, all now on public display in the centre.
The hot water shaped every later layer. Khan Krum took Serdica for the First Bulgarian Empire in 809, and it became Sredets, a Slavic name linked to the word for "middle". It passed to Byzantium in 1018, back to Bulgaria in 1194, and to the Ottomans in the 1380s. The current name comes from the 6th-century Church of Saint Sofia, Greek for "wisdom", and appears in documents from the 14th century. Under the Ottomans, Sofia was from 1530 to 1836 the seat of Rumelia Eyalet, the province that governed the empire's European lands, and 16th-century sources list hammams, the largest covered market in the Balkans, eight Friday mosques and three synagogues.
The most direct link to the springs is Banya Bashi Mosque, designed by Mimar Sinan and completed in 1566. Its name refers to the baths, and it was built directly over thermal springs; steam can still be seen rising from vents near its walls. It is the only mosque in the city still in use. Nearby, the Central Mineral Baths, designed by Petko Momchilov and Friedrich Grünanger in a mix of Vienna Secession and Bulgarian-Byzantine ornament, opened on 13 May 1913 and served as the public baths until 1986. After years of closure and restoration, the building has housed the Sofia History Museum since September 2015. The mosque, the Sveta Nedelya Church and the Sofia Synagogue stand within a few hundred metres of one another, a cluster locals call the "triangle of religious tolerance".
Vitosha, the Mountain on the City's Southern Edge
If the springs explain where Sofia began, Vitosha explains how it feels. The massif is a dome about 19 km long and 17 km wide, built up in tiers of plateaus that meet at Cherni Vrah, the "Black Peak", at 2,290 m; twelve of its summits pass 2,000 m. It also forms the watershed between rivers draining to the Black Sea and those draining to the Aegean. Vitosha Nature Park, the oldest in the Balkans, covers 266 km², roughly half of it inside Sofia's municipality, and two cable cars run from the city's edge year-round. Ski slopes were added in the 1970s and 1980s.
The mountain's foothills are part of the city. Knyazhevo, on its lower slopes, has mineral springs of its own. The quarter of Boyana holds the Boyana Church, a UNESCO World Heritage site since 1979, whose mid-13th-century wing was commissioned by the sebastokrator Kaloyan and his wife Desislava; its walls show 89 scenes with 240 human figures. Vitosha Boulevard, the pedestrian shopping street of the centre, is named after the mountain it runs toward.
Why the Crossroads Won in 1879
By the 19th century the springs and roads had not been enough to keep Sofia large. Its population fell from about 70,000 in the late 18th century to 19,000 in 1870, and a Russian army census in February 1878 counted just under 11,700 people. Russian forces under General Iosif Gurko took the city from the Ottomans on 4 January 1878, after a handful of foreign diplomats and residents refused to leave and so helped stop Suleiman Pasha from burning it.
The main alternative was Tarnovo, capital of the medieval Second Bulgarian Empire, which Austrian diplomats favoured. The scholar Marin Drinov, then serving in the provisional Russian administration, argued instead for Sofia, and it was accepted as capital on 3 April 1879. Sofia's assets were the ones described above: a central position in the Balkans on the main road between Europe and Constantinople, with room to grow on the valley floor. In 1880 it was only the fifth-largest town in the country, behind Plovdiv, Varna, Ruse and Shumen, but it overtook Plovdiv in 1892. The Alexander Nevsky Cathedral, whose foundation stone was laid in 1882 and which was mostly built between 1904 and 1912 in memory of the Russian soldiers of 1877–78, became one of the symbols of the new capital and of Bulgaria; it covers 3,170 m². The old crossroads logic still holds. The Central Railway Station is the hub of the national network, with Line 1 running to Plovdiv and Line 2, the country's longest, to Varna on the Black Sea, and the city has 186 km of railway lines in all.
Mladost, Lyulin and Druzhba: Filling the Valley Floor
After the communist Fatherland Front took power in 1945, migrants from the countryside poured into the capital, and the city spread across the basin in prefabricated housing estates such as Druzhba, Mladost and Lyulin. Of Sofia's 607,473 dwellings, 287,191 were built between 1970 and 1989 alone. Today the capital holds around 17 percent of Bulgaria's population, and few residents have local roots; those who do, the Shopi of the surrounding villages, speak Western Bulgarian dialects.
The same basin that protected the town now traps its air. The mountains on every side limit the movement of air masses, and in winter temperature inversions hold a lid of smog over the valley, fed by solid-fuel heating and traffic. Sofia's particulate and nitrogen oxide levels are among the highest in Europe. The valley's rainfall is moderate, about 626 mm a year, peaking in late spring and early summer thunderstorms. For the rest of the country beyond the basin, from the Black Sea coast to the Rhodopes, continue with our Bulgaria country guide, or test yourself on the top facts about Bulgaria.
Quick Facts About Sofia
- Country: Bulgaria
- Continent: Europe (Eastern Europe)
- Country population: approximately 6.7 million
- Capital city status: Sofia is the capital of Bulgaria, the seat of national government, and the location of foreign embassies, parliament, and the head of state's official residence.
Frequently Asked Questions
What is the capital of Bulgaria?
The capital of Bulgaria is Sofia. Sofia is the seat of national government, hosts most foreign embassies and consulates, and is typically where the head of state and parliament are located.
What continent is Sofia in?
Sofia, the capital of Bulgaria, is located in Europe, in the Eastern Europe region. As Bulgaria's capital, Sofia serves as the country's primary connection to the broader Europen political, economic, and cultural sphere.
Why is Sofia the capital of Bulgaria?
Sofia was chosen as the capital of Bulgaria for reasons that typically combine geography, history, and politics. Capital city selections often reflect a desire for centrality (being accessible from across the country), historical importance (being a longstanding seat of government or culture), or neutrality (being acceptable to multiple regions or ethnic groups within the country). The specific reasons for Sofia's designation are detailed in the city's history above.
What is Sofia known for?
As the capital of Bulgaria, Sofia is best known for housing the country's central government institutions — parliament, presidential or royal residences, supreme court, and key ministries. It is also typically a major cultural and economic center within Bulgaria, hosting national museums, embassies, and signature monuments. The introduction and history sections above provide detailed coverage of the city's specific notable institutions and landmarks.
Related Pages
- Bulgaria Country Guide — full geography, climate, economy, and culture overview
- Flag of Bulgaria — meaning, history, and design of Bulgaria's national flag