SIENA, Italy — The two remaining towers of a highway bridge in central Genoa that collapsed last year, killing 43 people, were demolished on Friday, clearing the city’s skyline of a grim landmark and preparing for the reconstruction of a vital urban transport link.

The sound of three low, ominous sirens broadcast on national television preceded the detonation.

Experts set a series of controlled explosions that in less than a minute brought down the nearly 300-foot-tall concrete towers that supported the 1960s structure, known as the Morandi Bridge for its designer, the famed engineer Riccardo Morandi. Its collapse last Aug. 14 has become the subject of a criminal inquiry, as well as a symbol of Italy’s failure to maintain its aging infrastructure and of shortcomings in how it has privatized roadways.

More than 1,300 pounds of explosives were mostly packed into the towers’ pylons. Demolition experts had prepared the site by creating lagoons to keep enormous clouds of concrete dust from spreading across the neighborhood.

The top politicians in Italy’s populist government — vice prime ministers Matteo Salvini of the League and Luigi Di Maio of the Five Star Movement — did not miss the chance to be part of the day. They both viewed the momentous demolition from another bridge near the site, surrounded by a swarm of local politicians and authorities.