Warsaw is home of one of the newest metro systems in the world. It opened in 1995 , and has expanded it’s one line ever since, currently the system has 21 stations on it’s single line. Out of the 40 trains running (in the entire system), 15 consist of the older Russian-produced cars, 7 of the newer Russian-produced cars and 18 of Alstom-produced cars. The Russian and Alstom carriages are incompatible and cannot be used in the same train. Personally, we prefer the older Russian model.