"Ponte Dona Maria", as it is commonly known, is a railway bridge built in 1877 by Gustave Eiffel. Yes, the one with a famous tower in Paris named after his name.
As The Guardian remembers, its construction resulted from a simple need – a railway line had to be brought across the river Douro and it was impossible to build piers on the river bed.
Gustave Eiffel devised an arch wider than any previously built, its structure widening where the forces are greater, with the dead-straight line of the tracks above.
One of the best places to admire the Maria Pia bridge is in Ribeira. Know more.