The only underground in the Czech Republic that connects the most busiest places in the centre of a city including four the most important railway stations. A construction was started in 1965. The first rail cars started driving on 09.05.1974 namely on the first section of a line C between Florenc and Kačerov. Prague metro has three gradually built and running extended lines: line A-green, line B-yellow, line C-red. The lines altogether three times come through under a level of Vltava river-on the line A at a depth of 14,5 m, on zje line B at a depth of 25 m and on the line C at a depth of 4-12 m.