The 25 de Abril Bridge (Ponte 25 de Abril, 25th of April Bridge, Portuguese pronunciation: [ˈpõt(ɨ) ˈvĩt i ˈsĩku ðɨ ɐˈβɾiɫ]) is a suspension bridge connecting the city of Lisbon, capital of Portugal, to the municipality of Almada on the left (south) bank of the Tagus river. It was inaugurated on August 6, 1966, and a train platform was added in 1999. Because it is a suspension bridge and has similar coloring, it is often compared to the Golden Gate Bridge in San Francisco, US. It was built by the American Bridge Company which constructed the San Francisco–Oakland Bay Bridge, but not the Golden Gate. With a total length of 2,277 m, it is the 27th largest suspension bridge in the world. The upper deck carries six car lanes, while the lower deck carries two train tracks electrified at 25 kV AC. Until 1974, the bridge was named Salazar Bridge. The name "25 de Abril" commemorates the Carnation Revolution.

The 25 de Abril Bridge is based in part on two San Francisco Bay Area bridges: its paint is the same International Orange as the famous Golden Gate Bridge; and its design is similar to that of the San Francisco–Oakland Bay Bridge. Both the Bay Bridge and the 25 de Abril Bridge were built by the same company. The American Society of Civil Engineers says that "Like its sister bridge, the SFOBB in San Francisco, the Tagus River Bridge is located in an area with a long history of earthquakes" and seismic data had to be taken into account in its construction. Another sister bridge is the Forth Road Bridge in Edinburgh.

Upon completion, the bridge had the longest suspended span and the longest main span in Continental Europe, the world's longest continuous truss, and the world's deepest bridge foundation. It was the fifth-largest suspension bridge in the world, the largest outside the US. Today it is the 27th largest suspension bridge in the world.

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