This stunning bridge connecting Porto, Portugal and its sibling Vila Nova da Gaia across the Douro River is a great place for a view of both cities and the river; its upper deck is now only for pedestrians and trams, while the lower deck is still open for traffic. The view below is from the bridge into old fortifications on the Porto side.
When it was built (by Gustave Eiffel’s associate, Teophil Seyrig) in 1886, it was the longest single-arch span in the world, and is still one of the highest. It’s often mistaken for its near-match, Eiffel’s Maria Pia railroad bridge a short distance up the river.