The Dom Luis I Bridge is a double-deck metal arch bridge that spans the Douro River in Porto, Portugal. The bridge was named after King Luís I of Portugal and was designed by the Belgian engineer Théophile Seyrig, who was a disciple of Gustave Eiffel.

The bridge is one of the most iconic landmarks of Porto and has become a symbol of the city. It connects the historic Ribeira district on the south bank of the Douro with the city of Vila Nova de Gaia on the north bank, which is home to many of the famous port wine cellars.

The bridge was completed in 1886 and has a total length of 385 meters (1,263 feet) and a height of 85 meters (279 feet) above the river. The upper deck of the bridge is used by Porto's metro system, while the lower deck is open to pedestrians and vehicles.

The views from the top of the bridge are stunning, offering panoramic views of Porto, the Douro River, and the surrounding hills. The bridge is especially popular at sunset when the sky is filled with hues of orange and pink.

Visitors can also take a guided tour of the bridge, which includes a visit to the upper deck and a walk through the old railway tunnel. The bridge has become a popular tourist attraction, and it is often crowded with visitors taking photos and enjoying the views.