Porto is bridge heaven. There are six bridges across the River Douro of which the Dom Luís I Bridge (Ponte D. Luís I) is a two-deck bridge that carries the metro line I featured a few posts ago as well as road traffic on its lower level.
It being a very nice day we enquired about the length of the boat trip available on the nearer boat in the above pictures and having plenty of time decided to go for it.
From that vantage point we got closer to the north bridge support buttress:-
The one below is from the bridge’s Wikipedia page and the last photo is of a distant viaduct bridge somewhere across the Douro which I had taken on the way down to the river:-