A holiday home built within a ruined 12th-century Warwickshire castle was handed Britain's biggest architecture award, the Riba Stirling Prize - the first time a conservation project has triumphed.
Astley Castle near Nuneaton - wrecked by a fire in 1978 - had been in danger of collapse until it was brought back to life by the £1.35 million building project for the Landmark Trust.
Judges of the prize said the winning design dealt with the ruins with "intelligence and practicality", and adding to them architecture which is "rich, visually beautiful and tactile".
It is the first time a house has collected the award and is the debut win, and appearance on the six-strong shortlist, for Witherford Watson Mann Architects.
The castle beat a huge revamp of Sheffield's Park Hill 1950s high-rise blocks, the Giant's Causeway visitor centre and the early favourite, a chapel for an order of nuns in Cuddesdon, Oxfordshire, to win the prize which rewards the year's best new building.
The property is a fortified manor building which has been in ruins since the fire and was on the Heritage At Risk Register. Due to the number of additions over the centuries it was difficult to know which period to emulate as a simple restoration, so architects stablised the ruins and set their new design within the shell.
The winner was announced at a ceremony at Central Saint Martins in King's Cross, London.
Stephen Hodder, president of the Royal Institute of British Architects, said: "Astley Castle is an exceptional example of how modern architecture can revive an ancient monument.
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"It is significant because rather than a conventional restoration project, the architects have designed an incredibly powerful contemporary house which is expertly and intricately intertwined with 800 years of history. Every detail has been carefully considered, from a specific brick pattern to the exact angle of a view, resulting in a sensually rich experience for all who visit. This beautiful new building is a real labour of love."
The judges' citation for the winner said: "Witherford Watson Mann has managed at once to respect the past, to be gentle in its relationship, while simultaneously not being afraid to make its architectural presence felt, and with some force.
"It has dealt with Astley's ruins with intelligence and practicality, while adding to them with a contemporary architecture that is rich, visually beautiful and tactile."