The Monday Map: 80 years of Moscow Metro maps
Metro.ru is a project by the Russian designer Artiom Lebedev. It was started in 1996 and is regularly updated. It features an extensive collection of maps of the metro of Moscow of the past 80 years.
The first one is from 1931 and the latest one is the official one released last year. It's really amazing to see the evolution of the map but also all the "unofficial" maps that were designed during the soviet era.