Brutalism—a movement informed by a utilitarian approach to public space and defined by imposing, functional structures cast in raw concrete—enjoyed its London heyday from the 1950s to the ’70s, most notably in architectural landmarks such as the Barbican and the Trellick Tower. The vast expanses of gray and plentiful right angles that are the signature of these mid-20th-century building blocks hardly conjure visions of child’s play, but a new exhibition at London’s Royal Institute of British Architects (RIBA) reexamines the thinking behind the unconventional playgrounds once found on these historic sites.

A re-created form at “The Brutalist Playground,” an exhibition by Assemble and Simon Terrill. Photo: Tristan Fewings/Courtesy of Getty Images for RIBA

“The Brutalist Playground,” which opens tomorrow, presents an immersive landscape inside RIBA’s Architecture Gallery, exploring the abstract structures that constituted play environments within the Brutalist vision. Designed by Turner Prize–nominated design-and-architecture collective Assemble and artist Simon Terrill, the installation re-creates some of the shapes and forms found on these playgrounds of the past, albeit in rigid foam and shades of pastel.

Balfron Tower playground photographed in 2015. Photo: Courtesy of Assemble and Simon Terrill

Assemble and Terrill used RIBA’s extensive archives to research and recast a diverse array of play elements; the historic source materials, from photographs to building plans, are also on display as part of the exhibition.

A Brutalist-style slide created for the exhibition. Photo: Tristan Fewings/Courtesy of Getty Images for RIBA

“A lot of the things we re-created aren’t obvious—they are these very unusual forms,” says Joe Halligan of Assemble. “It’s almost a kind of condensed Brutalism, and that’s what’s really cool—that it’s free architecture without constraints, so you see the fun that the architects had making these amazing structures. With this exhibition we hope to shine a light on these forgotten and largely demolished playgrounds and start a conversation about their value in play today.”

Through August 16 at the Architecture Gallery at RIBA, 66 Portland Place, London; architecture.com/RIBA*