Courtesy Royal Institute of British Architects (RIBA)

American architect Neave Brown is best known for his modernist high-density housing designs across the U.K.—especially his 1968 brutalist housing complex Alexandra Road Estate in London. Winner of the 2018 Royal Institute of British Architects (RIBA) Royal Gold Medal for Architecture, Brown died on Tuesday following a battle with cancer. He was 88 years old.

“The architecture community has lost a giant,” said RIBA president Ben Derbyshire in a press release. “Neave was a pioneer: He showed us how intellectual rigor, sensitive urbanism, his supreme design skill, and determination could deliver well-being to the local community he served so well in Camden.”

The Utica, N.Y.–born architect earned his degree from London’s Architectural Association School of Architecture and began practicing in 1950. In his projects, Brown often prioritized designing to create a community; ensuring front doors faced the routes and streets of a city, and that inhabitants benefited from private outdoor space—as evidenced by his design for Alexandra Road.

“His ideas, for low-rise high-density housing with private outside space for all residents, still stand as a radical antidote to much of the unthinking, not to say degrading, housing product of the era,” Derbyshire said.

Though he ceased practicing 15 years ago, Brown was nominated for—and ultimately won—RIBA’s 2018 Royal Gold Medal for Architecture, the U.K.’s highest honor for architecture recognizing a lifetime of achievements. At the time of his nomination, the current residents of his Alexandra Road complex submitted a letter of support for his work.

Brown’s entire portfolio is listed on the Statutory List of Buildings of Special Architectural or Historic Interest, according to RIBA.

The architecture and planning community has already taken to social media to grieve the architect: