The Dom Luís I Bridge was constructed between 1881 and 1886 with two decks, the upper deck being for pedestrians, trams and cars and the lower deck also for cars. The cars seemed to get the best deal there. Anyway, in 2003 the cars were chucked off the top deck of the bridge (not literally I hasten to add) to allow for better integration with the metro system.
This also had the result of allowing pedestrians to walk along the bridge without the fear of being run over by a car. Pedestrians can still be run over by a metro service, but these things are loud and more infrequent in number, so the odds are still in the favour of walkers.
And the upper deck of the bridge allows for some wonderful views along the Douro River. These photos don’t really do justice to how beautiful that view is, but here they are anyway.