Hillwood is associated with the heiress Marjorie Merriweather Post, who purchased the 24.4-acre estate in 1955 and had its interiors entirely renovated by Alexander McIlvaine of New York to provide an appropriate setting for her extensive collection of French and Russian art. The “refurbishing” of the interiors, which comprise thirty-six rooms, at a cost of $680,000 was probably a complete rebuilding. McIlvaine designed them in an eclectic range of neo-Beaux-Arts styles, but primarily in the popular eighteenth-century French Rococo and Neoclassical styles considered at the time as the epitome of good taste.
The house was originally erected for Mrs. Henry Parsons Erwin by her mother, Mrs. Thomas Walsh (see Embassy of Indonesia), who had a twin mansion built on the other side of Rock Creek Park for another daughter, Mrs. David St. Pierre Gaillard. The architect of both houses seems to have been Jack Diebert, about whom no biographical information has been located.
Hillwood today is very grand in scale. There have obviously been additions, but it is unclear where, when, or by whom. Diebert designed Abremont in a free rendition of the American Neo-Georgian style, two very tall stories in red brick. A very attenuated tetrastyle portico on the south or garden facade has columns based on the Grecian Tower of the Winds order, a simplified Corinthian capital with two levels of leaves and no volutes. A single-story north entrance porch spans the wide central projecting portico.
The mansion sits near the center of the