Porto "Ponte Dom Luis I." bridge. This bridge, built over 5 years and finally opened in 1886, became one of the symbols of Porto, and at the time was the longest iron arch bridge in the world. It was designed by Gustave Eiffel's pupil Teófilo Seyring. The upper deck is now used by the metro, while the lower deck is used by cars and pedestrians to cross the Douro River.
