The first railway in Portugal opened in 1856 between Lisbon's Santa Apolónia station and Carregado. Although the standard gauge of 1435mm had by then been adopted in several European countries, the new line used a broader gauge of 1664mm (5 Portuguese feet). Under British influence, some later lines were initially constructed to 1435mm gauge, but were later reconfigured to the broad gauge. The broad gauge did, however, allow interoperation with the Spanish network, which used a gauge of 1674mm. As speeds became higher in the late 19th / early 20th centuries the small difference in gauge became important, and so the systems of both countries were gradually reconfigured to a compromise gauge of 1668mm, which became known as Iberian gauge.
For reasons of economy, a number of metre gauge lines were constructed around the Douro valley in the north of the country. Some of those in the Porto area were converted to standard (1435mm) gauge in the early part of the 21st century to form the basis of the Porto Metro. Over a period of several years, the few remaining metre gauge lines operated by CP were closed to traffic. By 2019, only the line from Aveiro to Espinho-Vouga remained in operation, although this too is under threat of closure. There is a proposal to reopen a short stretch of one of the other lines, between Mirandela to Brunheda, as a tourist operation.
Photo image supplied by Best World Tourism