Designed to function like an outdoor public space, the Lawn comprises a scaffolding base that slopes up the museum hall and around its eight massive Corinthian columns, with an artificial turf laid on top.
Lawn will host a range of activities and events during its installation including movie nights, yoga and meditation, while wooden croquet mallets and balls are also available for playing games.
"The lawn is a fascinating example of a typology that straddles the line between public and private space," said Rockwell Group founder David Rockwell.
"Whether it is a backyard or a public green, lawns bring people together and foster a sense of community, so our goal was to create an indoor lawn that would inspire people to share stories, make memories, and daydream, while honouring the great tradition of summertime."
Rockwell Group's team has also added a number of furnishings, including the white deckchairs, umbrellas and blue rugs that are dotted around the grassy surface to encourage visitors to rest and relax.
Blue hammocks held in metallic cages are suspended from a 100-foot-tall (30-metre-tall) ceiling grid above the slope, providing a place for visitors to the museum rest. Each hammock is integrated with audio of American storytellers sharing summertime memories.
Lab has also developed a custom Augmented Reality game for kids and adults to imagine chasing and collecting fireflies throughout the lawn.
"The Lab has ingeniously brought a quintessentially American ideal into our Great Hall, highlighting the interplay between design and landscape, while also eliciting a sense of wonder and play among visitors of all ages," said the National Building Museum's executive director Chase Rynd.
A tall scaffolding structure built at the top of the hill rises up to the museum's third floor, offering views of the installation and activities.
A huge sign bearing the title "Lawn" also drapes down the rear of the structure, which blocks views of the hill from the museum's entrance. In this entrance, a glimpse of the install is instead provided by a large covering that resembles a pixelated skyscape.
Lawn is also designed to be as sustainable as possible. The grassy covering was provided by artificial turf company SynLawn, which uses a mix of sustainably grown sugarcane and a soybean-based backing system to create its product. The plant-based material is 100 per cent recyclable, according to the
Rockwell Group intends both the turf to repurposed after Lawn is de-installed, while the scaffolding will be re-used on other jobs once the exhibition ends.
Lawn is open 4 July to 2 September, and forms part of the sixth edition of the annual Summer Block Party series.
Rockwell Group, which was founded by Rockwell in 1984, is among a number of firms that have contributed to the museum's events series, following on from Snarkitecture's white fun house last year.
Photography is by Timothy Schenck.