The five-year, £80m restoration of the Big Ben tower in London has been nominated for the UKs leading architecture award, alongside a new fashion college campus, a science laboratory and an "inventive" home extension.
The refurbishment of Big Ben - officially known as the Elizabeth Tower - is among the six nominees for the Royal Institute of British Architects Stirling Prize.
The list also includes the London College of Fashion campus on the former Olympic Park in east London and AstraZenecas medical research centre in Cambridge.
They are joined by the "pioneering" Appleby Blue Almshouse retirement home and the Japanese-inspired Niwa House, both in south London, and an extension to an "eccentric" home in Hastings.
The Elizabeth line - Londons east-west train line - won the prestigious award last year.
The prize is given to the building judged to be "the most significant of the year for the evolution of architecture and the built environment", and is judged on criteria including design vision, innovation and originality.
It is usually given to a brand new building, but can also go to major restorations and renovations.
Other previous winners of the prize - first presented in 1996 - include Liverpools Everyman Theatre, Hastings Pier and the Scottish Parliament building in Edinburgh.
Riba president Chris Williamson said the shortlsted projects all "demonstrate architectures unique ability to address some of the most urgent challenges of our time, responding with creativity, adaptability and care".
Each offers "a blueprint for how architecture can enrich society", and they show a "hopeful vision for the future, one where architecture strengthens communities and helps shape a more sustainable and inclusive built environment", he added.
This social housing development, with 57 flats for over-65s, in Southwark, south London, replaced an abandoned care home, and is billed as a modern version of the traditional almshouse.
The design is intended to "foster community and reduce isolation among residents", Riba said, with communal areas and shared facilities including a kitchen and double-height garden room. "The result is a new standard for inclusive social housing in later life."
The Elizabeth Tower is one of Londons best-known landmarks and is often known as Big Ben - although thats actually the name of the bell that produces the famous bongs.
The most extensive works to the tower in its 160-year history included repairs to the clock mechanism; changes to the colour scheme on the four clock faces to put back the Victorian blue and gold; and reinstating St Georges Cross flag emblems. Accessibility improvements include a new lift.
The result is described as "a veritable masterclass in conservation and craftsmanship" by the judges - although it came at a cost, going way over its original budget, which was estimated at £29m to £45m.
This late 19th Century detached hillside house in the East Sussex town has been extended with a series of timber-framed rooms and industrial exterior features including a concrete yard and galvanised steel staircase.
"The result goes beyond a house extension, transforming the entire home and producing a lesson in restrained, inventive reuse," the judges said.
The college previously had six buildings but the 6,000 students and staff moved to the new 17-storey headquarters in the Queen Elizabeth Park in Stratford, east London, in 2023.
Judges approvingly noted features including its "dramatic staircases unfurling through a shared heart space to encourage collaboration".
This home, described as a "pavilion-like oasis", was built on a previously derelict plot behind a row of terraced houses in south London for a family with a love of Japanese design. It was also designed to be accessible for a wheelchair-using resident.
"The quality of light throughout the home is breathtaking," the judges said. "Large full-height sliding doors and full-height glazed walls seamlessly blend indoors and out – opening spaces to gardens, courtyards and balconies. It is difficult to see where the building ends and the gardens begin."
Medicine giant AstraZenecas Discovery Centre "radically redefines the research facility", according to Riba, "blending cutting-edge laboratories with welcoming public spaces".
The striking building has a curved three-sided shape, with a high, jagged exterior glass front and roof. Inside, three glass-lined labs are linked by "clever interconnecting corridors that balance stringent security with transparency, putting science on display".