The four-station line will run underground from Praça da Liberdade near São Bento main line station to Casa da Música via Plaza de Galicia and Hospital de Santo António.

Sener says the design of the station at Praça da Liberdade will be a significant challenge due to its location in the city centre, which is a UNESCO World Heritage Site.

Due for completion in 2022, the €181m project is one of two extensions to the Porto Metro network currently under development. Line G is forecast to carry around 33,000 passengers per day.