Spain and Portugal - Oporto, Bridge of Luis - View of metal arched bridge , houses in Background B/W. Part of Box 149 Boswell collection - Portugal and Spain. The Lu?s I (or Luiz I) Bridge (Portuguese: Ponte Lu?s I or Luiz I) is a metal arch bridge that spans the Douro River between the cities of Porto and Vila Nova de Gaia in Portugal. At the time of construction its span of 172 m was the longest of its type in the world.