A reinforced concrete frame defines the twisting form of a tower designed by local studio Hamonic + Masson & Associés for the port city of Le Havre in northern France.

Called the Alta Tower, the residential building has a prominent position in the city at the centre of Le Havre's 20th-century postwar masterplan designed by French architect Auguste Perret.

At 55 metres tall, the tower is the third-tallest structure in the city centre – a UNESCO World Heritage Site – after the Perret-designed St Joseph church and the Le Havre town hall.

The twisting structure is made from a reinforced concrete frame

"The port of Le Havre is the horizon. It is the sea and the sky that come together," studio founder Jean-Christophe Masson told Dezeen.

"Alta presents a new high point in the city and so it had to convey this dynamism."

The Alta Tower was designed to make a "bold and expressive statement", the studio added.

The tower forms the third-tallest structure in the city centre

Hamonic + Masson & Associés' design for the tower builds on Perret's reinvention of Le Havre, and responds to a nearby cultural centre with curvaceous forms designed by architect Oscar Niemeyer.

The resulting ascending twist was designed to combine Perret's gridded streets and buildings with Niemeyer's sinuous curves, using concrete in a nod to the city's existing architecture.

"The plot is located at a pivotal point in the history of the reconstruction of Le Havre," said Masson. "Sitting at the junction of the two urban grids of the general plan proposed by Perret, the location gives the building a singular character and geometry."

"[The tower] combines the form and sensuality of Niemeyer, [and] the grid and order of Perret, with concrete being the material common to all three projects," he continued.