Sofia is the capital and largest city of Bulgaria. It is situated in the Sofia Valley at the foot of the Vitosha mountain, in the western part of the country. The city is built west of the Iskar river and has many mineral springs, such as the Sofia Central Mineral Baths. It has a humid continental climate.
Known as Serdica in antiquity, Sofia has been an area of human habitation since at least 7000 BC. The recorded history of the city begins with the attestation of the conquest of Serdica by the Roman Republic in 29 BC from the Celtic tribe Serdi. During the decline of the Roman Empire, the city was raided by Huns, Visigoths, Avars, and Slavs. In 809, Serdica was incorporated into the First Bulgarian Empire by Khan Krum and became known as Sredets. In 1018, the Byzantines ended Bulgarian rule until 1194, when it was reincorporated by the Second Bulgarian Empire. Sredets became a major administrative, economic, cultural and literary hub until its conquest by the Ottomans in 1382. From 1530 to 1836, Sofia was the regional capital of Rumelia Eyalet, the Ottoman Empire's largest and most important province. Bulgarian rule was restored in 1878. Sofia was selected as the capital of the Third Bulgarian State in the next year, ushering a period of intense demographic and economic growth.
Sofia is the 14th-largest city in the European Union. It is surrounded by mountains including Vitosha to the south, Lyulin to the west, and the Balkan Mountains to the north. It is the fourth highest European capital after Andorra la Vella, San Marino and Madrid. Sofia is home to several universities, cultural institutions and commercial companies. The city has been described as the "triangle of religious tolerance". This is because three temples of three major world religions—Christianity, Islam and Judaism—are situated close together: Sveta Nedelya Church, Banya Bashi Mosque and Sofia Synagogue. This triangle was recently expanded to a "square" and includes the Catholic Cathedral of St Joseph.
The Boyana Church in Sofia, constructed during the Second Bulgarian Empire and holding much patrimonial symbolism to the Bulgarian Orthodox Church, was included on the World Heritage List in 1979. With its cultural significance in Southeast Europe, Sofia is home to the National Opera and Ballet of Bulgaria, the National Palace of Culture, the Vasil Levski National Stadium, the Ivan Vazov National Theatre, the National Archaeological Museum, and the Serdica Amphitheatre. The Museum of Socialist Art includes many sculptures and posters that educate visitors about the lifestyle in communist Bulgaria.
The population of Sofia declined from 70,000 in the late 18th century, through 19,000 in 1870, to 11,649 in 1878, after which it began increasing. Sofia hosts some 1.28 million residents within a territory of 500 km2, a concentration of 17.9% of the country's population within the 200th percentile of the country's territory. The urban area of Sofia hosts some 1.5 million residents within 5,723 km2, which comprises Sofia City Province and parts of Sofia Province (Dragoman, Slivnitsa, Kostinbrod, Bozhurishte, Svoge, Elin Pelin, Gorna Malina, Ihtiman, Kostenets) and Pernik Province (Pernik, Radomir), representing 5.16% of the country territory. The metropolitan area of Sofia is based upon one hour of car travel time, stretches internationally and includes Dimitrovgrad in Serbia. The metropolitan region of Sofia is inhabited by a population of 1.6 million.
Names
For a long time, the city possessed the name, Serdica (Ancient Greek: Σαρδική, Serdikē, or Σαρδική, Sardikē; Latin: Serdica or Sardica), derived from the tribe Serdi, who were either of Thracian, Celtic, or mixed Thracian-Celtic origin. The emperor Marcus Ulpius Traianus (53–117 AD) gave the city the combinative name of Ulpia Serdica; Ulpia may be derived from an Umbrian cognate of the Latin word lupus, meaning "wolf" or from the Latin vulpes (fox). It seems that the first written mention of Serdica was made during his reign and the last mention was in the 19th century in a Bulgarian text (Сардакіи, Sardaki). Other names given to Sofia, such as Serdonpolis (Byzantine Ancient Greek: Σερδῶν πόλις, "City of the Serdi") and Triaditza (Τριάδιτζα, "Trinity"), were mentioned by Byzantine Greek sources or coins. The Slavic name Sredets (Church Slavonic: Срѣдецъ), which is related to "middle" (среда, "sreda") and to the city's earliest name, first appeared on paper in an 11th-century text. The city was called Atralisa by the Arab traveller Idrisi and Strelisa, Stralitsa, or Stralitsion by the Crusaders.
The name Sofia comes from the Saint Sofia Church, as opposed to the prevailing Slavic origin of Bulgarian cities and towns. The origin is in the Greek word sophía (σοφία, "wisdom"). The earliest works where this latest name is registered are the duplicate of the Gospel of Serdica, in a dialogue between two salesmen from Dubrovnik around 1359, in the 14th-century Vitosha Charter of Bulgarian tsar Ivan Shishman and in a Ragusan merchant's notes of 1376. In these documents, the city is called Sofia, but, at the same time, the region and the city's inhabitants are still called Sredecheski (Church Slavonic: срѣдечьскои, "of Sredets"), which continued until the 20th century. The Ottomans came to favour the name Sofya (صوفيه). In 1879, there was a dispute about what the name of the new Bulgarian capital should be, when the citizens created a committee of famous people, insisting for the Slavic name. Gradually, a compromise arose, officialisation of Sofia for the nationwide institutions, while legitimating the title Sredets for the administrative and church institutions, before the latter was abandoned through the years.
Geography
Sofia City Province has an area of 1,344 km2, while the surrounding and much bigger Sofia Province is 7,059 km2. Sofia's development as a significant settlement owes much to its central position in the Balkans. It is situated in western Bulgaria, at the northern foot of the Vitosha mountain, in the Sofia Valley that is surrounded by the Balkan Mountains to the north. The valley has an average altitude of 550 metres (1,800 ft). Sofia is the second highest capital of the European Union (after Madrid) and the third highest capital of Europe (after Andorra la Vella and Madrid). Unlike most European capitals, Sofia does not straddle any large river, but is surrounded by comparatively high mountains on all sides. Three mountain passes lead to the city, which have been key roads since antiquity, Vitosha being the watershed between Black and Aegean Seas.
A number of shallow rivers cross the city, including the Boyanska, Vladayska and Perlovska. The Iskar River in its upper course flows near eastern Sofia. It takes its source in Rila, Bulgaria's highest mountain, and enters Sofia Valley near the village of German. The Iskar flows north toward the Balkan Mountains, passing between the eastern city suburbs, next to the main building and below the runways of Vasil Levski Sofia Airport, and flows out of the Sofia Valley at the town of Novi Iskar, where the scenic Iskar Gorge begins.
The city is known for its 49 mineral and thermal springs. Artificial and dam lakes were built in the twentieth century.
While the 1818 and 1858 earthquakes were intense and destructive, the 2012 Pernik earthquake occurred west of Sofia with a moment magnitude of 5.6 and a much lower Mercalli intensity of VI (Strong). The 2014 Aegean Sea earthquake was also noticed in the city.
Climate
Sofia has a humid continental climate (Köppen climate classification Dfb; Cfb if with −3 °C isotherm) with an average annual temperature of 10.9 °C (51.6 °F).
Winters are relatively cold and snowy. In the coldest days temperatures can drop below −15 °C (5 °F), most notably in January. The lowest recorded temperature is −31.2 °C (−24 °F) (16 January 1893). On average, Sofia receives a total snowfall of 98 cm (38.6 in) and 56 days with snow cover. The snowiest recorded winter was 1939/1940 with a total snowfall of 169 cm (66.5 in). The record snow depth is 57 cm (22.4 in) (25 December 2001). The coldest recorded year was 1893 with an average January temperature of −10.4 °C (13 °F) and an annual temperature of 8.2 °C (46.8 °F).
Summers are quite warm and sunny. In summer, the city generally remains slightly cooler than other parts of Bulgaria, due to its higher altitude. However, the city is also subject to heat waves with high temperatures reaching or exceeding 35 °C (95 °F) on the hottest days, particularly in July and August. The highest recorded temperature is 40.2 °C (104 °F) (5 July 2000). The hottest recorded month was July 2012 with an average temperature of 24.8 °C (77 °F). The warmest year on record was 2024 with an annual temperature of 12.5 °C (55 °F).
Springs and autumns in Sofia are usually short with variable and dynamic weather.
The city receives an average precipitation of 625.7 mm (24.63 in) a year, reaching its peak in late spring and early summer when thunderstorms are common. The driest recorded year was 2000 with a total precipitation of 304.6 mm (11.99 in), while the wettest year on record was 2014 with a total precipitation of 1,066.6 mm (41.99 in).
Environment
The geographic position of the Sofia Valley limits the flow of air masses, increasing the chances of air pollution by particulate matter and nitrogen oxide. Solid fuel used for heating and motor vehicle traffic are significant sources of pollutants. Smog thus persists over the city as temperature inversions and the mountains surrounding the city prevent the circulation of air masses. As a result, air pollution levels in Sofia are some of the highest in Europe.
Particulate matter concentrations are consistently above the norm. During the October 2017 – March 2018 heating season, particulate levels exceeded the norm on 70 occasions; on 7 January 2018, PM10 levels reached 632 μg/m3, some twelve times the EU norm of 50 μg/m3. Even areas with few sources of air pollution, like Gorna Banya, had PM2.5 and PM10 levels above safe thresholds. In response to hazardous spikes in air pollution, the Municipal Council implemented a variety of measures in January 2018, like more frequent washing of streets. However, a report by the European Court of Auditors issued in September 2018 revealed that Sofia has not drafted any projects to reduce air pollution from heating. The report also noted that no industrial pollution monitoring stations operate in Sofia, even though industrial facilities are active in the city. A monitoring station on Eagles' Bridge, where some of the highest particulate matter values were measured, was moved away from the location and has measured sharply lower values since then. Particulates are now largely measured by a network of 300 sensors maintained by volunteers since 2017. The European Commission has taken Bulgaria to court over its failure to curb air pollution.
History
Prehistory and antiquity
The area has a history of nearly 7,000 years, with the great attraction of the hot water springs that still flow abundantly in the centre of the city. The Neolithic village in Slatina dating to the 5th–6th millennium BC is documented. Another neolithic settlement was founded in the 3rd–4th millennium BC near the site of the modern National Art Gallery, which has been the traditional centre of the city ever since.
The earliest tribes who settled were the Thracian Tilataei.
In the 500s BC, the area became part of a Thracian state union, the Odrysian kingdom from another Thracian tribe the Odrysses.
In 339 BC Philip II of Macedon destroyed and ravaged the town for the first time.
The Celtic tribe Serdi gave their name to the city. The earliest mention of the city comes from an Athenian inscription from the 1st century BC, attesting Astiu ton Serdon, i.e. city of the Serdi. According to the inscription and to the writings of Dio Cassius, the Roman general Crassus subdued the Serdi and behanded the captives.
Dio Cassius, Pliny the Elder and Ptolemy say that in 27–29 BC Crassus attacked the region "Segetike", which is assumed to be Serdica, or the city of the Serdi. The ancient city is located between TZUM, Sheraton Hotel and the Presidency. It gradually became the most important Roman city of the region. It became a municipium during the reign of Emperor Trajan (98–117). Serdica expanded, as turrets, protective walls, public baths, administrative and cult buildings, a civic basilica, an amphitheatre, a circus, the City council (Boulé), a large forum, a big circus (theatre), etc. were built. Serdica was a significant city on the Roman road Via Militaris, connecting Singidunum and Byzantium. In the 3rd century, it became the capital of Dacia Aureliana, and when Emperor Diocletian divided the province of Dacia Aureliana into Dacia Ripensis (at the banks of the Danube) and Dacia Mediterranea, Serdica became the capital of the latter. Serdica's citizens of Thracian descent were referred to as Illyrians probably because it was at some time the capital of Eastern Illyria (Second Illyria).
Roman emperors Aurelian (215–275) and Galerius (260–311) were born in Serdica.
The city expanded and became a significant political and economical centre, more so as it became one of the first Roman cities where Christianity was recognised as an official religion (under Galerius). The Edict of Toleration by Galerius was issued in 311 in Serdica by the Roman emperor Galerius, officially ending the Diocletianic persecution of Christianity. The Edict implicitly granted Christianity the status of "religio licita", a worship recognised and accepted by the Roman Empire. It was the first edict legalising Christianity, preceding the Edict of Milan by two years.
Serdica was the capital of the Diocese of Dacia (337–602).
For Constantine the Great it was 'Sardica mea Roma est' (Serdica is my Rome). He considered making Serdica the capital of the Byzantine Empire instead of Constantinople. which was already not dissimilar to a tetrarchic capital of the Roman Empire. In 343 AD, the Council of Sardica was held in the city, in a church located where the current 6th century Church of Saint Sophia was later built.
The city was destroyed in the 447 invasion of the Huns and laid in ruins for a century. It was rebuilt by Byzantine Emperor Justinian I. During the reign of Justinian it flourished, being surrounded with great fortress walls whose remnants can still be seen today.