Grimshaw has completed the renovation and expansion of Duke University's West Campus Union in Durham, North Carolina, where the UK firm has added a glass box in the centre of the historic building.

The university's union building and surrounding areas were updated to reinstate it as the heart of the campus.

First opened in 1931, the West Campus Union was designed by American architect Horace Trumbauer's office as a hub for the university.

It formed part of a masterplan by Frederick Law Olmstead, the landscape architect behind New York's Central Park.

Grimshaw's reconfiguration of the building involved retaining and preserving Trumbauer's original stone facades – complete with ornate window tracery and gargoyles – but adding a new central core.

"These historic elements now frame a transparent atrium that provides a focal point for the building and surrounding academic precinct," said the firm, founded by Nicolas Grimshaw in 1980.

Large blackened-steel portals were inserted into the existing stone walls to create links between the wings and the atrium, improving circulation.

"This new network of connections creates a buzz of movement and interaction around the building, cultivating a palpable energy that defines the revived student community," Grimshaw said.

Steel and glass balconies provide seating areas below gothic-style wooden roof trusses, while a series of glass bridges create links between previously hard-to-reach rooms.

The union houses a range of dining facilities – boasting 12 venues that serve different international cuisines.

Original cafeteria style kitchens in the centre of the building were removed and replaced with exposed cooking stations.

Dining areas spill out onto Crown Commons – an outdoor space to the south of the building that also includes a beer garden.

Conference rooms, small group meeting areas and multi-purpose spaces are spread throughout the building for the university's clubs and societies to make use of.

"The renovation and expansion of West Campus Union marks a significant architectural intervention that aspires to connect, preserve, and sustain student life," said Grimshaw, which is also working on a high-rise school on the outskirts of Sydney.

The firm's proposal for London's Heathrow Airport was recently given the go-ahead, while its other ongoing projects include a pavilion for the Dubai 2020 Expo and a horse "theme park" in South Korea.

Photography is by James Ewing.