Location: London, United Kingdom

Design Team: David Chipperfield Architects

Gross Floor Area: 48,000 m²

Completion: 2025

Category: Hotel, Heritage Adaptive Reuse

Client: Qatari Diar

User: Rosewood Hotel Group

Structural and Facade Engineering: AKT II

Heritage Consultant: Turley Associates

Public Realm Consultant: Publica Associates

Landscape Consultant: Building Design Partnership

Hotel Specialist: Reardon Smith Architects

Photography: Simon Menges

Design Features: 30 Grosvenor Square stands in Mayfair, London, within the former United States Embassy designed by Eero Saarinen and completed in 1960. Portland-stone frames, an expressed concrete diagrid and Theodore Roszak's gilded eagle gave the purpose-built embassy a civic presence on the historic square. Diplomatic use, however, gradually surrounded it with barriers, vehicle defences and closed streets. After the embassy relocated, David Chipperfield Architects transformed the Grade II-listed landmark into The Chancery Rosewood through a strategy of conservation and adaptive reuse.

The first intervention concerns the building's relationship with the city. Security measures accumulated over decades, together with the original perimeter glacis, were removed to restore a direct address to Grosvenor Square. Retail, restaurants and bars occupy the lower levels and meet a renewed public realm. A building once defined by controlled distance is brought back toward street and pedestrian life; the most consequential change is not a theatrical entrance, but the gradual withdrawal of its defensive boundary.

Inside, the renewal begins with Saarinen's most distinctive surviving element: the exposed concrete diagrid ceiling. Office partitions added over time were stripped away, allowing the structure to be read continuously and extended into the enlarged public floor of the hotel. Reception, bar, lounge, restaurants and flexible event space now share this open piano nobile, recovering the original ambition of a 'palace on the park'. David Chipperfield Architects led the restoration, architectural transformation and spatial planning; detailed fit-outs for guestrooms, lobby and restaurants were developed by separate interior-design teams.

The upper floors were largely rebuilt behind the retained facade, with guestrooms arranged around a new central atrium. Ballroom, spa, retail, parking and plant occupy the basement. An extended sixth floor continues the established facade rhythm at a taller proportion to form a new crown, while a set-back pavilion above accommodates principal suites and shared facilities. The addition draws on an early Saarinen proposal, turning an unbuilt strand of the original design into the basis for contemporary change.

More than 4,000 Portland-stone facade elements were dismantled, cleaned, repaired and reinstated as the envelope was upgraded. Gold-anodised aluminium at the penthouse echoes the existing palette and the restored gilded eagle. Achieving BREEAM Outstanding, the project brings heritage reuse, hotel operation and environmental performance into the same architectural argument. What survives is therefore more than a modernist image: it is the civic memory of a building learning to inhabit a different public life.

Design Team: David Chipperfield Architects was founded in London in 1985 by British architect David Chipperfield, who studied at Kingston School of Art and the Architectural Association before working with Richard Rogers and Norman Foster. Chipperfield received the RIBA Royal Gold Medal in 2011 and the Pritzker Architecture Prize in 2023. The practice now comprises five independent offices in London, Berlin, Milan, Shanghai and Santiago de Compostela, locally embedded yet connected by shared architectural ambitions.

Its work is defined by process and discourse rather than a predetermined formal language. Client ambitions are mediated with the social, cultural, ecological and physical context of each commission. Reuse, durability and future adaptability remain central concerns, while heritage is understood to include material fabric, everyday memory and urban identity. Collaboration, critical review and sustained research into existing conditions provide the framework for architecture of restraint and clarity.

At 30 Grosvenor Square, project directors David Chipperfield, Louise Dier, Billy Prendergast, Benito Blanco, Alasdair Graham and Mattias Kunz worked with project architects Ryan Butterfield and Florian Dirschedl. AKT II provided structural and facade engineering; Turley Associates advised on heritage; Publica Associates and Building Design Partnership contributed public-realm and landscape expertise; Reardon Smith Architects served as hotel specialist. Rather than staging a confrontation between old and new, the team restored structure, withdrew defensive boundaries and continued the building's urban order, allowing Saarinen's work to retain historical depth through a new use.