The public transportation system in Bucharest has its origin in the 19th century, with the city introducing horse-drawn trams in 1872.

[10] The first proposals for a metro system in Bucharest were made in the early part of the 20th century, by the Romanian engineers Dimitrie Leonida and Elie Radu.

[12] The outbreak of World War II, followed by periods of political tensions culminating with the installation of communism, put an end to the plans.

A commission was set up, and its conclusion pointed to the necessity of an underground transit system that would become the Bucharest Metro.

Despite this, many stations are rather dark, due to the policies of energy economy in the late 1980s, with later modernisations doing little to fix this problem.

After the 1989 Romanian Revolution, the socioeconomic and political turmoil of the 1990s largely stagnated the expansion of the metro.

The fourth metro line, M4, for which construction was started in September 1989 (shortly before the Revolution), was finally opened in 2000.

After Romania joined the European Union in 2007, EU funds helped with the expansion of the metro.

Due to Bucharest being one of the largest cities in the region, the network is larger than those of Prague, Warsaw, Budapest or Sofia.

The first line, M1, opened on 19 November 1979, running from Semănătoarea (now Petrache Poenaru) to Timpuri Noi.

[14] The largest one, Piata Unirii, is cathedral-like, with vast interior spaces, hosting retail outlets and fast-food restaurants and has an intricate network of underground corridors and passageways.

As of 2023, the entire network runs underground, except for a stretch between Dimitrie Leonida and Tudor Arghezi stations on the southern end of the M2 line.

The network is served by six depots, two being located above ground (IMGB and Industriilor) and four underground (Ciurel, Străulești, Pantelimon and Valea Ialomiței) and smaller additional works at Gara de Nord 1, Eroilor 1, Republica, Parc Drumul Taberei, Favorit, Anghel Saligny, Crângași, Piața Victoriei 2 and Dristor 2 stations.

The metro network and the national rail network have almost similar track gauge (using the 1,432 mm / 4 ft 8+3⁄8 in vs 1,435 mm / 4 ft 8+1⁄2 in) and loading gauge but not the same electrification system (the metro uses 750 V DC third rail[a] whereas the Romanian Railways use 25 kV 50 Hz AC overhead lines) making it possible for new metro cars to be transported cross country as unpowered railway cars.

The system uses an IPU (Interlocking processing unit), TI21-M track circuits and EbiScreen workstations.

Other features include auto turnback and a balise system, called PSM (precision stop marker).

The last trains on M1, M2 and M3 wait for the transfer of the passengers between lines to complete, before leaving Piața Unirii station.

[citation needed] Like the STB, the metro can get crowded during morning and evening rush hours.

Starting from 29 July 2021 Metrorex began replacing the magnetic stripe cards with contactless ones for weekly and monthly passes.

A recent one on 25 June 2019, led to the disruption of metro traffic at rush hour between Piața Unirii and Eroilor (the suicide took place at Izvor).

These incidents led to criticism of METROREX, and suggestions to install platform screen doors or to increase security.

[56] The shortest distance between two adjacent stations is between Gara de Nord 2 (M4) and Basarab 2 (M4) and is 430 meters.