Guimarães is linked to Porto by the Guimarães railway line. This railway line was originally built with narrow gauge track, then modernised and rebuilt to the broad Iberian gauge in the first decade of the 21st century. The train service is operated by Comboios de Portugal. Locally, Guimarães is served by TUG (Transportes Urbanos de Guimarães) which operates 21 bus routes serving the city.