Metro do Porto, also known as the Porto Metro, is a rapid transit system serving the city of Porto and several municipalities in the Greater Porto area in Portugal. It started its operations on December 7, 2002. Since then, it has undergone significant expansions, adding new lines and stations to the network over the years. The Porto Metro system consists of six lines (A, B, C, D, E, and F) covering a total length of around 67 kilometers. It serves important areas in Porto, including the city center, suburbs, and municipalities like Matosinhos, Maia, Vila Nova de Gaia, and Gondomar. The metro system is integrated with other modes of public transportation, such as buses and trains, creating a comprehensive public transportation network in the Porto metropolitan area.