The first subway station was mapped in OpenStreetMap eleven years ago. Since then, people have been adding station and routes in each of 170 cities with subway or light rail systems. But only a few months ago the mapped routes were first used for routing. Unsurprisingly, the quality of data was bad. In this talk Ilya will explain the subway mapping principles, show common errors, talk about the community's reaction to tidying up metro systems, and present the tool to extract metro routes from OSM into easy-to-use data structures, which is used for the MAPS.ME application.