The double-decker Dom Luis I bridge is an icon of the city of Porto. It spans the River Douro linking the Port wine houses of Vila Nova de Gaia with the bustling downtown Ribeira district of Porto.
Construction took place between 1881 and 1886 with the bridge being built adjacent to an existing bridge which it replaced. The granite pillars of the original bridge are still in place, standing on the Ribeira like a pair of gate posts.
With a span of 172 metres (564 ft) and a height of 44.6 metres (146 ft) this was a great feat of engineering. The designer this time, Téophile Seyrig, had been Eiffel's partner on the previous project and showed himself to be a more than able engineer with this bridge.
One of the notable features of the Ponte Dom Luís I is it's two levels; one on top of the arch and the other suspended below it. Both decks were initially intended to carry road traffic but these days the top carries the Porto Metro trains as well as having a pedestrian walkway. It is worth making the crossing on the upper level, although being 60 metres (190 ft) above the waters of the Douro, it might not be for everyone!