Warsaw Metro consists of one line only but I personally could not imagine travelling around Warsaw without it.
It was opened in 1995 after 70 years of planning and building. The line is still under construction.
In relation to other subway systems, Warsaw metro is very clean, platforms are wide.
After many years Warsaw finally has its first subway line (Metro). The line operates from Kabaty in the southern part of Warsaw to the city hall (Plac Bankowy). The trains operate in 5 to 6 min. periods and move very fast from one stop to the other (1-1.5 min). The subway is surprisingly modern, kept clean, and is patrolled by the police (policja). The entrances to the stations are marked with a red "M" on a yellow background, which stands for subway. When entering the subway station one is expected to validate their ticket. Remember this because there are no ticket validators in the subway cars! You can be fined if you are caught without a ticket in the station or in the subway car. Incidentally, if you do want to ride without a ticket, you are most likely to get caught in the subway. the passengers in the subway are checked more frequently than in other forms of transportation.
Besides busses and tramways, there is the Metro as well. Unfortunately, Warsaw´s metro is a kind of neverending story ever since the city council decided on building it in the 1920´s. Certain historical events and low cash-flow afterwards prevented the realization of their plan until the mid-70´s. right now the underground public transport consists of exactly one line, heading from town hall to Kabaty in the south... it´s about a distance of 14 kilometres. Some things just take their time over here!