American artist and sculptor Richard Serra has died at his home in Long Island, New York, at the age of 85.
Considered one of his generation's greatest sculptors, the San Francisco native originally studied painting at Yale University but turned to sculpting in the 1960s, inspired by trips to Europe.
Serra was known for turning curving walls of rusting steel and other malleable materials into large-scale pieces of outdoor artwork that are now dotted across the world.
The artist's lawyer said the cause of death was pneumonia.
Known by his colleagues as the "poet of iron", Serra became world-renowned for his large-scale steel structures, such as monumental arcs, spirals and ellipses.
He was closely identified with the minimalist movement of the 1970s.
Serra's work started to gain public attention in 1981, when he installed a 120ft long and 12ft high curving wall of raw steel that splits the Federal Plaza in New York City.
The sculpture, called "Tilted Arc", generated a swift backlash from people who work there as well as demands for it to be removed.
The sculpture was later taken down, but Serra's popularity in the New York art scene had been cemented.
Most of Serra's large-scale works are welded in Cor-Ten steel, but he also worked with other non-traditional materials such as rubber, latex and neon - as well as molten lead, which Serra threw against a wall or floor to create his "Splash" series in his early career.
His works have been installed in landscapes and included in the collections of museums across the world, from The Museum of Modern Art in New York to the deserts of Qatar.
In 2005, eight major works by Serra were installed permanently at the Guggenheim Museum in Spain.
Carmen Jimenez, the exhibition organiser, said Serra was "beyond doubt the most important living sculptor".
Born to a Russian-Jewish mother and a Spanish father in San Francisco, Serra was the second of three sons in the family.
He started drawing at a young age and was inspired by the time he spent at a shipyard where his father worked as a pipefitter.
Before his turn to sculpting, Serra worked in steel foundries to help finance his education at the Berkeley and Santa Barbara campuses of the University of California. He then went on to Yale, where he graduated in 1964.
