The Hôtel de Monaco, acquired by William Williams Hope in 1837 from the Princess of Eckmühl, widow of Louis-Nicolas Davout, Marshall of the Empire under Napoleon, was built for the Princess of Monaco by the architect Alexandre-Théodore Brongniart (1739-1813) in 1774. Not finding it to his taste, Baron Hope completely changed its layout and interior decoration. The mansion’s refurbishment, costing 7.5 million francs, was completed in 1841.
State of the art plumbing and a bathroom made it one of the modern buildings of the period. Two side wings were added, built by the architect Achille-Jacques Fédel (1785-1860), a Prix de Rome laureate in 1813 and a former pupil of Brongniart. The new 12,000 square-metre mansion now extended from 131 to 133 rue Saint-Dominique and 15 to 17 rue d’Iéna.
When Baron Hope inaugurated his new residence on 25 April 1842, his guests included the kingdom’s greatest families, the Rohans, the Gontauts, the Noailles, the La Trémoilles and the Richelieus. His private apartment was on the ground floor, with the main staircase leading up to the reception rooms on the first floor. Outside there were gardens, greenhouses, ornamental ponds, pavilions and even a riding school for his thirty-five horses.
When the baron died in 1855, the mansion was sold at auction to Baron Seillière, who bequeathed it to his daughter, Princesse de Sagan. It was later the home of the great antique dealer Jacques Seligmann, then bought by the State and allocated to the Polish Embassy in 1936.