Yep - thats it - locks on the river Douro - all the way from the Portugese west coast at Porto through the whole of Portugal into Spain.
The engineering it astonishing.
These pics taken from one of the Douro river cruise ships - carries around 100 passengers/crew.
I cant fully remember but there are about 5 locks between the sea and the Spanish border.
These two are the Carrapatelo at 35 metres and the Bagauste at 27 metres - real engineering masterpieces.
This one with the mobo shows the sheer scale
These shots are of a downstream ship is entering at the top - just a small amount of concrete keeps this ship from falling over 100 ft into the valley below.
They have a neat way of securing the ships and boats in the locks - using bollards that float up with the water in the lock.
Hope this post wasnt too boreing
I find engineering on this scale fascinating.