WATES is negotiating a £20 million deal to build a care home in west London for the Royal Hospital Chelsea.
The firm has seen off competition from Laing O'Rourke, Walter Lilly and Galliford Try to secure the deal to build the 125-bed home.
Designed by Sir Christopher Wren, the hospital was originally built in 1692 to provide a service for old and injured soldiers.
It has subsequently become home to the Chelsea Pensioners and the world famous Chelsea Flower Show has been held in the hospital's grounds since 1913.
The exterior of the new building has been designed by Quinlan and Francis Terry Architects.
American firm Steffian Bradley Architects is designing the interior and overseeing the project.
Demolition of the old infirmary building has already begun and construction work is anticipated to start next month.