He commissioned French architect René Sergent in 1910 to design a mansion in the Palermo section of Buenos Aires, and contracted the Parisian interior designer André Carlhian and landscaper Charles Thays.
In addition, he designed the headquarters for the Rolls-Royce Limited, a Parisian store for the Duveen brothers (1907–1908) in the form of a Petit Trianon at the rear of a marble courtyard at n° 20 place Vendôme which is now a bank headquarters, and the Duveen Gallery, a large building in the style of Ange-Jacques Gabriel at the corner of 5th Avenue and 56th street in New York City (1909–1910, demolished 1953).
René Descartes | René Char | René Magritte | François-René de Chateaubriand | René Goscinny | Leon René | René Jacobs | Rene Daalder | Rene Russo | René Lévesque | Rene Requiestas | René Kollo | René Clausen | René Clair | Rene Portland | René Clemencic | Rene Auberjonois | René Higuita | Rene Goulet | René Girard | François-René de La Tour du Pin, Chambly de La Charce | Sherie Rene Scott | René Sergent | René Rémond | René Lussier | René Laennec | René II, Duke of Lorraine | Rene d'Harnoncourt | René de La Tour du Pin | Otis René |
n° 19: A private mansion built in 1913, in the neo-classic style, by René Sergent for Alfred Heidelbach which currently houses the galleries of the Japanese and Chinese Panthéon Bouddhique of the Guimet Museum.
After having rejected a project in the Anglo-Norman style by the architect René Sergent, then a first project in a medieval style (drawings in the collection of the Musée d'Orsay), Halphen decided on the second design, by Guillaume Tronchet : a château in the Louis XVI style celebrating hunting on the exterior and music in the interior.