The Dom Luis I Bridge, or Luís I Bridge, is a double-deck metal arch bridge, built between the years 1881 and 1888 that spans the River Douro between the cities of Porto and Vila Nova de Gaia in Portugal. At its construction, its 172 metres span was the longest of its type in the world.
As the King of Portugal, D. Luiz I, did not appear at the inauguration, the people of Porto removed the Dom from the name of the bridge, which is why it is only called Luiz I. Bridge. Calling D. Luiz bridge is a common mistake but courage of the people of the city. At the entrance to the bridge of the lower deck it is engraved in the stone "Ponte Luiz I".