When the United States’ London embassy moves across town from Mayfair to Nine Elms in 2017, it will leave behind a monumental home: the Eero Saarinen–designed Chancery Building, the architect’s only project in the United Kingdom. David Chipperfield Architects’ proposed renovation of the building would transform it into a hotel with retail and event spaces, retaining Saarinen’s patterned Portland stone facade.

Under Chipperfield’s plan—commissioned by Qatar-based developer Qatari Diar—the building’s nine stories (three of which are belowground) would be converted into 137 guest rooms, five restaurants, six flagship retail units, a spa, and a 1,000-person ballroom. The renovation would also strip the property of existing security bollards and barricades, to turn the ground-level area into a welcoming, permeable public space.

Saarinen’s building is in Grosvenor Square, which has been the United States’ diplomatic home in London since the late 18th century. record called the design of the new embassy “the most important single project” in the State Department’s foreign buildings program (record, April 1956), but when it opened in 1960, it sparked controversy because its monolithic form stood out from neighboring neo-Georgian buildings.

Said David Chipperfield of the renovation, “Our design proposals protect and respect the significant architectural and structural characteristics of Eero Saarinen’s design, with a focus on restoring and enhancing this unique building to secure its long-term future at the heart of Mayfair.”

The firm’s proposal will be submitted to the Westminster City Council for approval this month.