The first master plan for a full metro network in Istanbul, titled Avant Projet d'un Métropolitain à Constantinople and conceived by the French engineer L. Guerby, dates to January 10, 1912. The plan comprised a total of 24 stations between the Topkapı and Şişli districts and included a connection through the Golden Horn. Each station would have a 75-metre platform next to the rail line, while the distance between stations varied from 220 to 975 metres.