The idea of building a subway in Lisbon dates back to 1888, when engineer Henrique de Lima e Cunha proposed an underground rail network for the city. However, it was not until 1955 that construction began and the Lisbon Metro finally opened on December 29, 1959. Following small extensions in the 1960s and 1970s, expansion has been more rapid since the 1990s. Today, the Lisbon Metro has 4 lines with 26.8 miles of track and 55 stations.