The preparatory works for the development of the Metro were underway by the end of the thirties, sadly the war and its aftermath somewhat delayed its progress. In the sixties, serious discussions began regarding the type of Metro to be developed, whether this should be the Soviet type, or the so called light Metro (an underground tram), of Czech design. The heavy metro won in the end. The first part of C line was opened in 1974, Prague citizens nicknamed it the “centimetro”, sarcastically referring to the length of this first line. In the first year of its operation only 28 million citizens were transported by metro. The line was gradually extended and other lines were added so that by 1977, the metro transported over 100 million citizens. At that time, B Line, which today goes from Černý Most to Zličín, began to be built and one year later the first section of A line started operation. The Metro is under continuous development as new sections are added. Current plans involve the extension of A line to lead first of all to the hospitals in Motol, and then to Prague Airport. A new D line is being planned and this will support the over loaded C line which currently connects Letňany with Jižní Město although in the future it will connect Písnice and Libuš with the City centre.
Gradually the metro was also modernised, by the beginning of the nineties it transported over half a billion travellers per year. Security systems were improved. The old Soviet wagons began to be modernised as it became clear that the metro needed new wagons. The M1 prototype made its debut in 1998 and now this model runs on C line; it will gradually replace the obsolete wagons from the Russian Mytiščinsky plant. The metro underwent a severe test during the floods in 2002. On 13th August, water began to spill down into the stations; it was a tragic day which caused the central part of the Metro to be submersed by the flood. Still, some parts of the Metro remained in operation; in other places a replacement shuttle service was running and in others regular transport was used. After massive reconstruction efforts, the Metro was able to start operating fully in March 2003. The floods proved how intrinsic the Metro is for the life of the city. Yet, on the other hand, it was also a warning, namely, that it is not possible or desirable to solely rely on the Metro, it is necessary to develop additional above ground transport. In light of this, new plans for tram tracks received the green light.