The Royal Institute of British Architects has announced the six-strong shortlist for this year's Stirling Prize, which includes Renzo Piano Building Workshop's cube-shaped Paddington Square.

This year marks the 30th anniversary of the annual RIBA Stirling Prize, which is regarded as the highest architecture award in the UK.

As in previous years, all six shortlisted buildings vying for the prize are located in England – this year, two are located in London, two in Cambridge, one in Essex and one in Hertfordshire.

London-based projects include Paddington Square, a mixed-use building designed by architecture studios Renzo Piano Building Workshop and Adamson Associates, which has a 55- by 55-metre cube form made from an exposed steel structure and curtain walls.

The building completed in 2024, nine years after its design was first revealed, following periods of design changes, backlash from critics and a public inquiry that put its construction on hold.

This year is the second time Renzo Piano Building Workshop has featured on the Stirling Prize shortlist, after The Shard lost out on the award in 2014.

The second shortlisted project in London is Lion Green Road, a residential development in Croydon that contains both affordable and private residences, designed by Mary Duggan Architects and RUFF Architects.

The housing complex is made up of five brick buildings, each with apartments arranged in an angular, pinwheel shape around a central core.

Two University of Cambridge buildings made the shortlist this year, including the expansion of Pembroke College by Haworth Tompkins. The studio won the Stirling Prize in 2014 for the Everyman Theatre in Liverpool.

Haworth Tompkins' intervention at the Pembroke College involved retrofitting six existing buildings and adding six new buildings, which were connected by timber-framed cloisters.

Last year's Stirling Prize recipient Witherford Watson Mann Architects is hoping to continue its winning streak with its oak-framed extension at Cambridge's Grade I-listed Clare College.

The studio also previously won the prize in 2013 for its renovation of Astley Castle.

Marking the fifth time the studio has been shortlisted, Bennetts Associates is in contention for winning the Stirling Prize for its work with Citizens Design Bureau at the BEAM cultural centre in Hertford, which involved adding a cluster of brick volumes around a 1970s theatre.

Completing the six-strong shortlist is a brick home situated on the edge of Epping Forest by Sergison Bates, which also previously had a housing project featured on the 2023 Stirling Prize shortlist.

RIBA president Chris Williamson said the 2026 shortlist "shows us what architecture can achieve when creativity, purpose and public value come together".

"In their distinct ambitions to revitalise communities, transform public infrastructure, deliver exemplary housing, carefully evolve historic institutions and create a thoughtful new home, these projects show that UK architecture is not only defined by style, but by true impact on people and place," he continued.

"As the Stirling Prize marks its 30th year, this exceptional shortlist joins a distinguished legacy of projects that represent the very best of British architecture, where ambition, ingenuity and social responsibility combine to create places of lasting value."

First awarded in 1996, the annual RIBA Stirling Prize is given to "the architect of the building thought to be the most significant of the year for the evolution of architecture and the built environment".

The shortlist is selected from the winners of the RIBA National Awards, which this year included 32 winning buildings.