When the bridge officially opened on 6 August 1966, thousands of people gathered on both sides of the river to witness what was considered one of Portugal's biggest engineering achievements. At the time, it was inaugurated as the Salazar Bridge during the Estado Novo dictatorship. According to historian Luís F. Rodrigues, former Prime Minister António de Oliveira Salazar was initially reluctant to have the bridge named after him, but eventually accepted the decision.

The opening ceremony included the national anthem, a 21-gun salute, and live television coverage. A green Austin Seven became the first civilian car to cross the bridge, while around 50,000 vehicles used it on its first day. Following the Revolution of 25 April 1974, the bridge was renamed in honour of the date that brought an end to the dictatorship.

An engineering milestone

Although the idea of building a bridge across the Tagus dates back to the 19th century, construction only began in November 1962. Around 3,000 workers and 14 construction companies, including 11 Portuguese firms, completed the project in less than four years, finishing six months ahead of schedule.

The bridge was built under the technical direction of the US Steel Export Company consortium and quickly became one of the country's most ambitious public works projects. It was completed at a cost of 4.49 million contos, around €22.4 million at today's conversion.

Its resemblance to San Francisco's Golden Gate Bridge is no coincidence. Both bridges were built by the American Bridge Company and share similar suspension cables, steel towers and the distinctive reddish-orange colour. However, Lisbon's bridge was later expanded to include a railway deck.

The bridge's central span stretches for more than one kilometre, while its towers rise 196 metres above the Tagus. Engineers also faced major challenges during construction, digging through more than 30 meters of riverbed mud before reaching solid basalt rock to secure the foundations.

More than just a bridge

The bridge changed the way people travelled between Lisbon and the south bank, but its construction also came at a cost. Thousands of residents in the Alcântara Valley were displaced to make way for the bridge and its access roads.

Architect Nuno Teotónio Pereira was among those who criticised the process, accusing the dictatorship of carrying out evictions under poor conditions and rushing families into inadequate housing before the bridge's inauguration.

Although only road traffic used the bridge when it first opened, it had already been designed with rail transport in mind. Major works completed in 1998 widened the road deck to six lanes, strengthened the structure and added the lower railway deck. Fertagus trains began crossing the bridge the following year, creating the first permanent rail connection between Lisbon and the Setúbal Peninsula.

The opening of the Vasco da Gama Bridge in 1998 provided another route across the Tagus, but the 25 de Abril Bridge remains by far the busiest.

Still one of Portugal's busiest crossings

As communities on the south bank continued to grow, traffic steadily increased, reaching a record of more than 57 million vehicles in 2005.

Traffic dropped sharply during the COVID-19 pandemic, but it has since returned to normal. Today, around 150,000 vehicles and 174 trains cross the bridge every day, carrying more than 300,000 people between Lisbon and Almada.

Drivers have paid tolls since the bridge first opened in 1966. The original toll for a standard car was 10 escudos, compared with €2.25 today. Between 1996 and 2010, however, tolls were suspended every August following public protests over price increases and changes introduced under the Lusoponte concession.

Earlier this year, bridge users once again staged a horn protest after tolls increased by 2.29%, renewing calls for the charges to be abolished.

The 60th anniversary celebrations concluded on Thursday evening with a drone show above the Cristo Rei monument, celebrating one of Portugal's most recognisable landmarks and its continuing role in the daily lives of millions of people.