20 Mass
20 Mass
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Washington, D.C.
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The RMR Group
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500,000-SF urban, mixed-use development
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Ground-floor retail and restaurants create a vibrant streetscape
Four-star hotel and Class-A office space at penthouse level
Extensive green roof
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Master planning
Architecture
Interior design
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American Architecture Award, Chicago Athenaeum, 2025
Finalist, Royal Sonesta Hotel at 20 Mass, Hotel Over 200 Rooms Global Award, 2025
The International Hotel Global Architecture Design Awards, Silver Award, 2025Chicago Athenaeum American Architecture Awards, 2024
Engineering News-Record, MidAtlantic Best Project, Office/Retail/Mixed-Use, 2024
Rethinking The Future Awards, Third Award | Urban Design (Built), 2024
ULI Washington, Excellence in Mixed-Use Development Award, 2023
NAIOP DC Excellence Awards, 2023
Washington Business Journal, Best Renovation, 2023
20 Massachusetts Avenue NW, known as 20 Mass, is a transformative mixed-use redevelopment in the heart of Washington, D.C. Originally a 1970s seven-story government office building, the site has been reimagined as a vibrant, 10-story destination that seamlessly integrates retail, a four-star Royal Sonesta hotel, and Class A office spaces. The project completely gutted and modernized both the interior and exterior while retaining the existing structure, adding three new floors, and expanding the building’s footprint to 485,000 SF. A new glass curtainwall facade and two interior atria bring abundant natural light and create a dynamic indoor-outdoor connection, enhancing the pedestrian experience along Massachusetts Avenue and F Street.
Sustainability and wellness are at the core of 20 Mass’s design. The building is both LEED Gold and WELL certified, featuring high-performance glazing that reduces energy consumption by over 20%, low-flow water fixtures that cut water use by 40%, and a 23,000-SF green roof that captures rainwater and provides biophilic benefits. Materials were carefully selected to minimize embodied carbon and improve indoor air quality, while advanced ventilation and filtration systems further support occupant health. The Royal Sonesta hotel within the development utilizes prefabricated SurePods for guest rooms, minimizing construction waste. 20 Mass stands as a model for adaptive reuse, urban placemaking, and sustainable design in Washington, D.C.
