A metro system is an excellent demonstration of how the built environment can influence the quality of our daily lives. The construction of tunnels for trains is usually considered in isolation from the provision of circulation spaces for people, even though they are part of a continuous experience for the traveller, starting and ending at street level. Designed and constructed in two phases to create a pair of interconnecting underground lines along the banks of the River Nervión, the Bilbao Metro is unusual in that it was conceived as a totality: from the beginning, architectural, engineering, construction and graphic design skills were integrated within a shared vision.