From Wikipedia: https://en.wikipedia.org/wiki/Bilbao_tram

The Bilbao tram (Basque: Bilboko tranbia, Spanish: Tranvía de Bilbao) is a tram system in Bilbao, Basque Country, Spain. Operated by Euskotren under the brand Euskotren Tranbia (which also manages the tram system in Vitoria-Gasteiz), it comprises a single 7.8 km (4.8 mi) line, inaugurated on 18 December 2002[3] and last extended on 25 March 2022.[4]

The factor leading its creation was to improve Bilbao's railway network; the tram serves neighborhoods that do not have Metro Bilbao or Cercanías stations. Also, the line goes through important tourist and cultural spots, like the Guggenheim Museum Bilbao.[5] It offers connections with Metro Bilbao, Euskotren Trena and Cercanías Bilbao.