British studio Foster + Partners and local architect Luis María Uriarte have expanded the Bilbao Fine Arts Museum in Spain with a 55-metre-long elevated gallery.
Named Agravitas, the bridge-like extension sits on large V-shaped columns that straddle the existing museum, not touching the original building fabric.
Foster + Partners and Luis María Uriarte designed the extension to improve the connection between the museum's multiple buildings and extensions, which have a U-shaped layout with an extended wing.
"In the great tradition of Bilbao, a city with a rich industrial history and an outstanding ability to reinvent itself, this project is about bridging the past, present, and the future," said Foster + Partners founder Norman Foster.
"The flexible new building looks ahead to the future and responds to the ever-changing form of contemporary art, while remaining respectful of the site's storied history," he continued.
"Working in collaboration with local architect Luis María Uriarte and the museum teams, the design reinforces the museum's role as one of the city's major civic attractions, with enhanced permeability, expanded gallery spaces, and a new social heart for the museum."
Locally produced steel was used to build Agravitas, aiming to celebrate the industrial heritage of Bilbao.
The extension spans the existing museum and a former outdoor space at the centre of the complex, creating a ground-floor hall enclosed by a glazed facade and filled with sculptures.
The upper level contains column-free gallery spaces topped with skylights that can let daylight in or be blacked out depending on exhibition requirements.
Foster + Partners also introduced office space and roof terraces to give views across the city.
Overhanging roofs were designed for solar shading, while photovoltaic panels have been added to the rooftop.
The transformation also involved restoring Bilbao Fine Arts Museum's existing buildings and reopening the original 1940s entrance for the first time in decades.
Foster + Partners worked on the design for Agravitas with Spanish engineer Julio Martinez Calzón, founder of MC2 Estudio de Ingeniería, who passed away in 2023.
Other projects recently completed by Foster + Partners include an art gallery in Shanghai lined with tubular glass and the Zayed National Museum on Saadiyat Island, which is characterised by soaring ventilation towers.
The photography is by Nigel Young.