The Maria Pia bridge in Porto was constructed by Gustave Eiffel.

The Maria Pia Bridge in Porto, Portugal, was created by Gustave Eiffel, which is one of the interesting facts about Gustave Eiffel. He constructed the Maria Pia bridge, also called Ponte Dona Maria or Ponte Maria Pia, as a railroad overpass. One of the most visited tourist attractions in the entire city is the Maria Pia Bridge. Wrought iron was used to construct the bridge when it was first constructed in 1877. A more contemporary successor was built in 1991, therefore it is no longer in service as a rail bridge. Although it is no longer in service, the bridge was formerly a railway bridge.

The 353 meters (1,158 feet) long, two-hinged crescent-shaped, wrought-iron structure, which was suspended 60 meters (200 feet) over the River Douro, used to span the river for the railway to Lisbon. The world's longest single-arch span at the time of construction was this one. It was built "at the boundaries of the classical metal structure," according to Gustave Eiffel. Using cutting-edge techniques at the time, the inventiveness used in its creation established it as an engineering milestone.