Carolands in Hillsborough: A House Designed Around Rooms That Already Existed
By Matthew Martinez, Founder, CEO & Managing Broker, Diamond Real Estate Group. California DRE #01869679.
A room is usually designed as part of a new house and furnished afterward. At Carolands, important rooms existed before the building around them. Antique French interiors helped determine the proportions and arrangement of Harriett Pullman Carolan’s Hillsborough residence.
That reversal makes the house a particularly revealing architectural story. Its history involves designing, transporting, installing, removing and ultimately returning interiors, as well as constructing the building itself.
The interiors came before the completed design
The Carolands Foundation’s historical chronology records Carolan’s purchase of three antique salons in 1912, before the house was designed. Two were eighteenth-century rooms from a residence in Bordeaux, associated with architect Victor Louis.
The foundation explains that Ernest Sanson planned the house to accommodate those rooms and respect their proportions. A collection was therefore shaping architecture, rather than simply occupying spaces chosen independently.
This changes how a decorative interior should be understood. Paneling can belong to a particular geometry, including the relationship between doors, mirrors, fireplaces and wall divisions. Moving it into another building requires more than selecting a suitable paint color.
Design and construction had distinct responsibilities
The chronology identifies Sanson’s preliminary plans in 1913 and Willis Polk’s appointment as on-site construction manager in 1914. The distinction recognizes both the French design and its local execution.
A building of this complexity required the drawings and the construction process to meet. Crediting only the best-known local name would flatten that collaboration and obscure how the project crossed architectural cultures and geographic distance.
The rooms later left the building
The foundation records removal and storage of the antique salons in the late 1920s. Their absence contributed to stories that the house had never been finished. Two rooms were later reinstalled after Countess Lillian Remillard Dandini acquired their paneling.
This is a reminder that an empty interior can be misleading historical evidence. Missing finishes do not necessarily prove that an architect left the original work incomplete. They may reflect an episode in the building’s later life.
The same room can also carry two histories: its original creation and its installation within a later house. Both matter to understanding what survives.
The restoration added another deliberate layer
Decorator Mario Buatta’s first-person restoration essay describes beginning work with Ann and Charles Johnson in 1998. He distinguishes surviving French woodwork from newly applied wall finishes and explains that the ballroom’s planned paneling had been interrupted by the First World War.
The essay gives restoration a practical texture. It involved planning, specialist painters, upholstery and different treatments for different spaces. The result cannot be reduced to a single freshening-up project or an assumption that every surface is original.
Scale is part of the architecture
On the same preservation page, architectural historian Richard Guy Wilson emphasizes the experience of the stair hall and the relationship among house, garden and hills. His argument concerns what physical space can communicate beyond a photograph.
Proportion, sequence and the transition between rooms are architectural qualities in their own right. A photograph may show ornament clearly while giving little sense of how a person moves through the composition.
Hillsborough’s estate history includes craftsmanship and change
Carolands offers an unusually dramatic example, but the underlying questions apply more broadly: what was designed for the house, what was brought into it, and which later changes shaped the present experience?
Explore real estate and home for sale in Hillsborough and our older-home guide. Contact Diamond to discuss homes with attention to architectural character, accommodation and the history visible in their spaces.
Sources checked October 28, 2026. This account draws on the foundation’s history and published restoration essays; it reports no personal tour. Confirm access directly with the foundation.
