Holland Harvey has completed the extension and refurbishment of the Montcalm Mayfair, a Grade II-listed hotel set within a historically significant Georgian crescent at Wallenberg Place in central London. Originally constructed in the late 18th century as part of the Portman Estate, the crescent was partially destroyed during the Second World War. The northern end was rebuilt in the 1970s, when the buildings were converted into a hotel. Inserted behind the restored historic frontage, Holland Harvey’s contemporary infill extension reimagines the hotel’s rear with a ziggurat form that responds to the angular geometry of the post-war plan. The new addition, accommodating guestrooms, steps away from the existing structure in a series of terraces, featuring cast-glass panels that bring natural light into the interior while maintaining guest privacy. Pigmented GRC (glass-reinforced concrete) panels reference the surrounding material context, integrating the new volume within its urban setting. Externally, the Georgian façade—complete with original timber sash windows and classical porticos—has been carefully preserved. Whilst internally, the design removes previous unsympathetic interventions at ground floor level, reinstating the building’s original scale and proportions. New open-plan layouts are filled with daylight and include reinstated features such as a “Morning Room”, informed by historical research. The hotel features 151 thoughtfully crafted guest rooms, including three signature suites, as well as the restaurant, Lilli by Akira Back and YATRA SIGNATURE spa. Themes of botany and the idea of a “Georgian garden” are woven throughout the project, inspired by the site's proximity to Hyde Park. Sustainability played a central role in the project. Holland Harvey partnered with social enterprise RAW Workshop to reclaim and reuse materials from the strip-out phase, embedding principles of circularity and social impact into the design process. Montcalm Mayfair is committed to responsible luxury with sustainability and community at its core, including energy-efficient systems and partnerships with social enterprises. The hotel is pursuing B Corp, Green Key and EarthCheck certifications, demonstrating its commitment to environmental stewardship and responsible hospitality. With the launch of Montcalm Mayfair, Montcalm Collection introduces a new concept of Sensitive Luxury to London’s hotel landscape. This refreshing new genre of softer, gentler luxury, sensitive to contemporary values and classic architecture, speaks to all the senses while delivering warm, welcoming, uplifting service.