Sofia is located in the Sofia Valley with an altitude of about 550 meters on a territory of 1,311 sq. km, of which populated areas and urbanized territories occupy 245.5 sq. km, agricultural land - 509 sq. km, forest areas - 466.5 sq. km, mining areas - 40.5 sq. km, territories for transportation and infrastructure - 20.6 sq. km and watercourses and water areas - about 40 sq. km.
Sofia Valley is rich in iron ores, building materials and lignite. The building materials are sand, gravel, hearting stone, limestone and clays.
The region is rich also in mineral waters.
A number of low rivers cross the territory of Sofia. Their beds within the bounds of the city were corrected. Bigger are Iskar, Vladayska, Perlovska, Suhodolska, Slatinska, Boyanska, Bistarska and Bankyanska rivers. The main drainage artery is the valley of the Iskar River located along the meridian. Hydro-mineral resources on the territory of Sofia occupy a significant share of those of the country (15 fields with total mineral water consumption - 130 litters per second).
Black-earth troughs, alluvial-meadow and colluvial -meadow soils predominate in the plains of Sofia Valley. Cinnamon and brown forest soils are typical of the middle-mountain areas.
The capital of the Republic of Bulgaria is a unique city that grows but not get old and has more than 7000 years of history.
Came into being (Established) round a hot mineral spring, at the crossroads of extremely important roads linking Western Europe with Asia Minor and the Middle East and the Baltic Sea with the Aegean Sea, the city of Sofia has seen and remembers lot. It is a millennial perseverance, which very few European cities can be proud of.
In the New Stone Age (Neolith) - VI-V century BC, the closest among the numerous prehistoric settlements in Sofia Valley is today's neighbourhood of Slatina. Remnants of the next copper-stone age (Chalcolith) - IV-III century BC, were discovered much closer to today's metropolitan centre, at the now lowered terrace near “Knyaz Alexander Battenberg" square, where the buildings of the National Art Gallery and the National Ethnographic Institute with museum are located.
The Thracian town, which grew out of the ancient Neolithic settlements that came into being around the preserved until today thermal springs, later was called Serdica by the Romans, i.e. town of the Serdi, named after the inhabiting it Thracian tribe. Though few, the finds from this epoch testify to the presence of a flourishing Thracian settlement in the area between the TZUM and the Sheraton Hotel. This epoch marks the beginning of the historical city centre of Sofia, which has not changed its location to this day.
Since 45 AD, the territory inhabited by the Serdi passed to the newly formed Roman province of Thrace. The provincial lands were administratively divided into strategies - areas called by the names of the tribes that inhabited them. The city thrived first as a centre of administrative district in the province of Thrace, and at the end of the III century it became the capital of the newly established province of Dacia Mediterranea.
Thanks to its location, the settlement rapidly developed economically, and as a result, after the year 106, under Emperor Marcus Ulpius Traianus (98-117), it received the rights of municipium - a settlement with autonomous management and urban organisation. In honour of the emperor, the town began to be called Ulpia Serdica and in official inscriptions it was called "the most glittering city of the Serdi".
In the second half of II century, between 176-180, during the joint rule of Emperor Marcus Aurelius and his son Commodus, the city was fortified with a wall. Its route, imposed by the natural configuration of the terrain, determined forever the permanent fortified urban area and layout - the place of the four fortress gates and the two connecting streets, the correctly oriented street network, the city quarters (insulae), the place of the city square (forum) and around it - the most important public buildings - the seat of the Roman deputy (praetorium), the city council (the bouleuterion), the Council of Chiefs (the gerousia), etc. The traces of this layout can be made out in the present routs and areas of main streets, boulevards and squares in the centre of Sofia. During the same II century, the hot mineral spring was capped, around which the public baths (thermae) were built. The historical development of the city was calm and flourishing until the 40s of the III century, when, for a period of about 30 years (239-270), invasions of tribes from the north of the Danube affected both the provinces of Moesia and Thrace and the urban territory of Serdica.
In the second half of the III century, occurred changes in the Roman Empire that directly affected the status of the city. Under Emperor Aurelian (270-275), the Roman garrisons were withdrawn out of the territory of present-day Romania, to the south of the Danube, and by 272 AD two new Roman provinces were organized - Coastal Dacia and Inland (Mediterranean) Dacia, with main city Serdica.
At the beginning of IV century, an eminent event, important for world history took place in Serdica. In April 311, Emperor Galerius, together with the emperors Licinius and Constantine, issued the Edict of Toleration, legalizing Christianity in the Roman Empire. Thus Serdica became the home of the Free Church and a kind of first Christian capital of the Roman Empire before Constantinople. Recently, this precedence of the Edict of Serdica has been increasingly highlighted in scientific and popular literature over the importance of the Edict of Milan which followed in 313, confirming the provisions of the Law issued in 311. It is noteworthy that Serdica was not only the capital of the Emperors Galerius and Licinius, but also the favourite city of Emperor Constantine the Great (born in the nearby Nis).
Constantine even intended to move his capital here, and ancient authors say that he often said, "Serdica is my Rome". It is very likely that Constantine's attachment to Serdica was due to a fact often highlighted by the writers, cartographers and poets of the early XIX century, namely that the Emperor's mother, St. Elena, was born in Serdica. In 343, Serdica became the seat of the very important Council of Serdica, attended by delegates from all over the Empire, and for a long time it was designated as Ecumenical. 282 bishops signed under the important decisions of the Council of Serdica, which probably took place in the Imperial Complex, whose ruins remain to this day around the Church of St George Rotunda. The rotunda was consecrated for Christian church around 330 AD and to this day it is the oldest acting church in the city and among the oldest acting churches in the world.
The times of Emperor Justinian I the Great (527-565) was the last period of the city's flourishing in antiquity. The fortification walls of the city were rebuilt, and on the hill to the east of the city stood in imposing height the basilica of Saint Sofia Church. By the end of the VI and the beginning of the VII century, the Slav tribes had settled in the Serdica region and the city continued to exist in a Slavic environment within the borders of the Eastern Roman Empire, Byzantium.
The Bulgarian Khan Krum (803-814) appreciated the strategic location of the city, besieged it in the spring of 809 and conquered it, but it finally became part of the First Bulgarian Empire during the reign of Khan Omurtag (814-831). The ethnic composition of the urban population changed and became predominantly Bulgarian. The new name, Sredets, is associated with that period - a transformation of the former name of the city to reflect its geographic location - in the middle of the Balkan lands, at the juncture of many roads. For almost two centuries Sredets had developed as an important political, military, economic and cultural centre of the First Bulgarian Empire.
After the Byzantine conquest in 972 of the north-eastern Bulgarian lands with the capital Preslav, Sredets became the temporary capital of the state and the Bulgarian Archbishopric, headed by Patriarch Damyan, moved here from the town of Drastar (present-day Silistra). During the period 1018-1194, when it was under Byzantine rule, the city did not lose its significance. It was the temporary seat of the Byzantine governor of the "themа (region) of Bulgaria", called the "Duke of Sredets".
During the Second Bulgarian Empire, there was a time of prolonged economic and cultural prosperity for Sredets (1194 - 1382). The city grew and finally took the look of a typical medieval city. The streets narrowed, appeared buildings with a characteristic brick - stone structure, new small churches were erected, and in the vicinity many monasteries appeared - mostly on the slopes of Vitosha and Stara Planina. In the last decades of the XIV century, the city began to be called with its present name – Sofia -by the name of the basilica, which rises nearby. The new name gradually replaced the older names - Serdica, Thriaditza, Sredets, and in the XV century it finally entered into common use.
Тhe new name Sofia was mentioned for the first time in a document of Dubrovnik in 1376, and in 1382, it was inscribed in a golden bull by Tsar Ivan Shishman, granting lands and tax exemptions to the Dragalevtsi Monastery of the Holy Mother of God of Vitosha.
In 1382, after a three-month siege, Sofia was conquered by the Ottoman conquerors. Under the new organisation of the invaded Balkan territories, Sofia became the centre of the largest administrative unit - the Beylerbeylik of Rumelia (eyalet), headed by pasha.
A year after the Liberation of the city from the Ottoman rule (04.01.1878), on April 3, 1879, the First Constituent National Assembly unanimously voted Sofia for the capital of the restored Bulgarian state.
In 1879, the first urban development plan of Sofia was drawn by the urban engineer S. Amadiet. It transformed the city's skyline and to a large extent shaped the outlook of today's city centre. For the construction of the new capital were recruited some of the most prominent architects and builders of that time - Konstantin Jovanović - Viennese architect of Bulgarian origin - designed the building of the National Assembly. The first urban architect, the Czech Antonin (Arnold) Kolář - designed the Ministry of War, the Hotel Bulgaria, the Military Club and others, and the Swiss, Herman Mayer designed the community centre “Slavyanska Beseda”, the buildings of the Bulgarian Academy of Sciences, the Bulgarian National Bank and the mausoleum of Prince Alexander Batenberg. The Austrian Vriedrich Grunanger designed the Theological Academy (Faculty of Theology) and was involved in the reconstruction of the Prince’s Palace. The architect Yordan Milanov, born in the town of Elena and graduated in Vienna, worked out the final design of the Sofia University Rectorate and managed the construction.
In 1891, on the design of the Chief Architect of Sofia, Arnold Kolář and Vaclav Prošek, was built the Eagle Bridge - the symbolic door of the city. The name came from the bronze statues of the eagles, which are its symbolic patrons and protectors. Eagle Bridge was built also as a symbol of freedom. There were welcomed the Diyarbakır prisoners, fighters for religious and national freedom.
After the Liberation, the Provisional Russian Administration in Bulgaria headed by the emperor’s commissioner, prince Dondukov-Korsakov, settled in Plovdiv, where he stayed from June to September 1878. The signing of the Treaty of Berlin required the relocation of the temporary governance, and prince Dondukov settled in Sofia in October of the same year.
According to the stipulation of Article 4 of the Treaty of Berlin, an assembly of the Bulgarian leaders was to be convened in Tarnovo to draw up the "Organic Rules of the Principality". The constituent assembly had to decide the issue of the capital city of Bulgaria.
The idea Sofia to remain the capital belongs to Prof. Marin Drinov. His merit in choosing Sofia as the capital city is undisputed. During the Liberation War, this great Bulgarian scholar, professor at Kharkov University and author of major historical works, was assigned to the Office of the head of civil governance of the occupied Bulgarian lands, prince Cherkassky. Furthermore, he enjoyed the personal sympathies of prince Dondukov, who placed a great confidence in Drinov and listened to his advice.
According to Drinov, Sofia's advantages for a capital city were several: it is situated in the centre of the Bulgarian lands and has an important strategic location, lies on the most important route on the Balkan Peninsula that connects Europe with Asia. The city is located in a large valley, which provides convenient terrain for expansion. Close to Sofia is the Pernik coal mine, which immediately after the Liberation began easily and quickly to supply coal for the industry, transport and heating.
Sofia was proposed at the session of the Constituent Assembly in Tarnovo on March 22, (April 3, according to the new calendar) 1879, when Nayden Gerov expressed the thought that "it is necessary to determine the capital of the Principality". No other proposal was made and Sofia was accepted unanimously and with enthusiasm.
In its centuries-long development, Sofia has always played an important role in the history of the Bulgarian lands as a centre, a natural intersection of the roads linking the East with the West, as well as the countries north of Bulgaria to that south of it. It is a unique city that is growing but it is not getting old and has more than 7 000 years of history.