The choice of Sofia as the capital of the newly liberated Bulgaria proved to be crucial for the development of the city. The people who are at the helm of the new capital want it to quickly become like the big and modern European cities. The arrival of progressive-minded and enterprising foreigners whose ideas and proposals were well received by the city government gave impetus to its rapid development, which began with electrification and the construction of an electrified tram system.

In 1898 the municipality signed concession contracts with a French company for the electrification of Sofia and with a Belgian company for the laying of an electric tramway. In two years, about 25 kilometres of track were built with the 1000 millimetre gauge then used in Belgium, rectifier stations for 600 VDC and a catenary with copper wire, as well as a depot on Boulevard. “Princess Marie Louise”. The track consisted of single tracks, with no turntables, and at the more main stops the road split into two tracks for diverging.

On 1 January 1901 (old style) a 2 route, single track with interchange tracks was opened at the more main stops, with the end stops having the trammen changing cabs and reversing the turntable as there were no turntables. On 1 April 1901, traffic was opened to Knyazhevo. By the end of 1901 traffic was running on a total of 6 routes. The rolling stock consisted of 25 new or refurbished Belgian tramcars and 14 tram trailers, class I and II. The then villages of Knyazhevo, Pavlovo, Krasno Selo and Poduyane (and later Vrabnitsa) became the first and only villages with a tram.

The townspeople welcomed the trams as a miracle. Here is how one newspaper describes this event: “Yesterday the inhabitants of the capital were spectators of a new phenomenon of worldly progress – the first tram cut almost the whole of Vitosha Street, the huge crowd admiring the pleasant sight of the tram’s speed and the bright sparks under its wheels and on the wire above. The tram runs fast, without a jerk, is electrically lighted and has exquisite furnishings.”

In 1908 Sofia received for the first time 6 large four-axle locomotives. Three of the Zeppelins (as they were then called) were destroyed in the bombing of 1944, and the remaining three operated until 1976.

The next delivery of trams were in 1914. 12 Charleroi locomotives and 15 trailers were delivered from Belgium.

On October 1, 1916, Sofia Mayor Radi Radev arrested the Belgian staff of the concessionaire of the contract for the electric tramway and seized the trams for the benefit of the city. The final transfer of the enterprise continued until 18 February 1927, when the “Directorate of Trams and Lighting” – “DTO” was founded.

The condition of the trams and the road, especially the old one, was poor. There was a danger of closure due to large deviations from the inter-rail. On the basis of measurements taken of the current condition, it was decided to average it out, with the new gauge becoming 1013 millimetres.

Between 1924 and 1931 more than 70 railcars were delivered from various European manufacturers, including Siemens and MAN, and 40 trailers manufactured by Siemens, MAN, Uerdingen and Energie. By design of Eng. Kardalev, head of the Repair Workshop and using frames and running gear from old scrapped ones, 12 tram trailers were built, summer type – with barred doors and without windows, which became known as “Kardalev trailers”.

In 1936, the production of tramcars began in the tram workshop. The first 6 units were made according to the documentation of the imported in 1924 “Siemens” locomotives, with some modifications: extended basket and increased engine power.

The last delivery of foreign-made tramcars to Sofia for many years to come was made in 1938. 20 “Breda” locomotives were delivered, which carried the citizens of Sofia until the 1970s.

In 1941 the city of Sofia began to satisfy its needs for tram rolling stock with its own production. The workshop in the “Krasno Selo” district began to produce tramcars alongside the repair of the old vehicles.

In 1951 the production of the modern for its time tram cars “Republic” began. A total of 20 locomotives and as many more trailers were produced, which operated until 1978.

With the accumulated experience, Tramway Plant – Sofia (TS Sofia) launched two more models of trams – “Komsomolets” in 1959 and “Cosmonaut” in 1961, which were the first articulated trams in the capital. Of the model “Komsomolets” 25 pieces were produced, and of the model “Cosmonaut” – 63 pieces.

In 1965 a new tramcar concept was launched. The “Sofia” model was the basic model and 175 articulated tramcars were produced. On the basis of the basic model in 1971 the production of the model “Sofia 70” was started – an axle tramcar with two articulated units, from which 180 trams were produced.

The development of the model continued with the creation of the “Sofia 100” multiple units. These are six-axle, single-articulated trams and are dedicated to the 100th anniversary of Sofia’s proclamation as the capital. Also dedicated to the anniversary, in honour of Bulgaria’s 13th anniversary, is the three-section model “Bulgaria 1300” built on the basis of the “Sofia 70” model, of which 26 trams were produced.

In 1985 the production of trams model T6M-700 began. The model retained the concept of the “Sofias”, but changes were made to the running gear – a new bogie was developed with group drive of the wheels. This model has variants both for the narrow gauge 1009 mm and for the newly built track with standard gauge 1435 mm.

As a result of the need for trams with increased capacity, some of the T6M-700 trams produced were upgraded with the addition of one section, thus becoming three-section trams and gaining the designation T8M-900. The last completely newly built tram in the Sofia tram factory left the factory in 1990, thus ending the history of tram building in Bulgaria.

In 1989, after a long interruption, the import of tram cars and trailers was resumed, mainly from the TATRA tram works in Czechoslovakia. At that time 37 T6B5 type locomotives were imported for the first newly built routes with a standard gauge of 1435 mm.

In 1990-1991 new 40 four-axle locomotives type T6A2-BG were delivered from Czechoslovakia, and in 2000 another 17 locomotives of the next model – T6A2-Sf, all for 1009 mm gauge.

After 1995, Sofia’s tram fleet began to be replenished with second-hand tram rolling stock. For the standard gauge in 1995, 29 units of four-, six- and eight-axle Duewag locomotives and trailers, manufactured in the period 1958-1975 and operated in various cities of Germany, were delivered. In 2003, 16 T4D locomotives, manufactured in the 1970s in Czechoslovakia and operated in Germany, were delivered. The Metropolitan Electric Transport fleet was supplemented in 2010 with 15 imported T4D-M multiple units and 15 B4D-M normal gauge trailers and in 2011 with 20 T4D-C multiple units and 20 B4D-C narrow gauge trailers, which were upgraded in the 1990s from T4D multiple units and B4D trailers.

A significant milestone in the history of trams in Sofia was the modernisation of T8M-900 trams, where they acquired a medium low-floor section. Between 1999 and 2007, 23 trams were modernized, which acquired the designation T8M-900M. Sofia was one of the first capital cities in the eastern block with low-floor trams!

In the period 2007 – 2009 the Czech company Inekon a.s. together with Tramcar modernized 18 T6M-700 six-axle locomotives, converting them into axle cars with a low floor middle section.

In autumn 2013, the first fully low-floor Pesa Swift tramcars for 1009 mm gauge were imported. With a length of more than 30 m and 5 sections, these are the longest locomotives operated in the more than 100-year history of tram transport in the capital.

As of 2016, according to the data of Stolichna Elektrotransport EAD, the following historic tramcars, trailers and shunting machines have been preserved: