The couple commissioned French architect René Sergent in 1911 to design a mansion for Errazúriz's future retirement from the diplomatic corps, in which he had been Ambassador to France for a number of years.

The ornate Neoclassical structure inspired the Bosch family to commission a similar palace nearby (today the United States Ambassador's residence).

The project of the building, a sample of pure eclecticism, was designed by the French architect René Sergent in 1911 but it was finished in 1917 due to the difficulties caused by the First World War.

The materials were brought from Europe: wooden panels, mirrors, marble, woodworks, frames, latches; a number of European artisans were called for some of the stucco decorations.

Its imposing and sober façade takes from the French Neo-classicism of the 18th century, especially from the works of Jacques A. Gabriel, architect in the Court of Louis XV.

Its sumptuous Louis XV style was accomplished including in its decoration Ionic pilasters, arcs and groin vault ceilings.

High windows with colored glass, the decoration of the ceiling, the imposing fireplace and the walls covered with tapestry and wood evoke the great English halls of the 16th century Tudor style.

The Dining-room: This luxurious room was planned bearing in mind the frequent dinners and social events offered by Mr. Matías Errázuriz and Mrs. Josefina de Alvear.

The texture and shades of the marble works replicated in this room by stucco decorations create a total harmony with the panels in the dining-room.

The Room of Madame: Comfortable chairs, armchairs, tables and boudoirs of Louis XVIII design were favored by Mrs. Josefina de Alvear's when receiving visitors.

In this Neoclassic room, Don Matías enjoyed his moments of solitary meditation, surrounded by paintings from the 19th century, Japanese lacquer decorations, and the Chinese hard stones.