Wikipedia " The Dom Luís 1st Bridge is an arch bridge that spans the Douro River between the cities of Porto and Vila Nova de Gaia. At the time of construction its span of 172 m was the longest of its type in the world.
The Government held a competition for the construction of a metallic bridge on the Douro River on a site that was adjacent to an existing bridge and would replace it. Teófilo Seyrig had already engineered the D. Maria Pia Bridge project, whilst working as a partner of Eiffel. He now took sole responsibility for the new, major Luis 1st Bridge. The construction was begun in 1881 and the bridge opened on 1886-10-31.
Total length 385.25 m
Weight 3045 tons
The arch measures 172 m in length and 44.6 m in height "