Ponte Dom Luís I
Time Out says
The double-decker metal bridge linking both the São Bento and Ribeira districts in Porto with Vila Nova de Gaia on the south bank was begun in 1881 and inaugurated five years later. It was designed by Teófilo Seyrig, an associate of Gustave Eiffel who had worked with the Frenchman on the Ponte Maria Pia, upriver (it self Eiffel’s first major work but no longer in use). The curve of the arch measures 172 metres; the bridge is almost 45 metres high. Metro trains between Porto and Gaia cross the river on its upper deck.