Moscow Metro - Life Below The Streets
The Moscow Metro, opened in 1935 with just one 11km line, now as of 2014 has 12 lines with 195 stations and 325km in length. Park Podeby is the deepest at 74m station (3rd in the world after after the Arsenalna in Kiev and Admiralteyskaya in St Petersburg). Built with typical Russian flamboyance, each station has its own theme.
Park Pobedy, aka Victory Park, metro station, not only the 3rd deepest in the world, but has 2 escalators , each 126m in length and is adorned by the mural of the Great Patriotic War or the Eastern Front as it was known in Germany. The header image is also from Victory Park.
My favourite one is the Dostoevskaya station, named after the great author Fyodor Dostoevsky, who wrote Crime and Punishment and The Idiot.
Controversial murals: silhouette of Rodion Raskolnikov on one of the walls, "running" down the stairs as if he wanted to escape from the terrible crime he's committed. Crime and Punishment scene, elderly pawn broker and her sister being murdered with an axe and the gun to the head suicide mural.
Mayakovskaya Metro Station is Moscow, considered to be one the most beautiful. Built in 1938 and named after the famous Russian poet, Vladimir Mayakovsky.