Ponte Dom Luis I Bridge. Built between 1881 – 1886, crossing the Douro river connecting Porto to Vila Nova de Gaia. The Arched, double deck, two-hinged bridge was designed by the Architects Theophile Seyrig and Leopold Valentin. Constructed of Wrought Iron the it spans 385.25m and weighs 3 045 t, with a total arch span of 172m. A figure of $369,000 has been quoted for the cost of construction.