William A. Clark, a wealthy entrepreneur and politician from Montana, commissioned the New York City firm of Lord, Hewlett & Hull to build the mansion in 1897.

The mansion contained 121 rooms, 31 baths, four art galleries, a swimming pool, a concealed garage, and a private underground rail line to bring in coal for heat.

[2] In addition, he imported marble from Italy, oak from Sherwood Forest in England, and parts of old French châteaux for the interior.

The mansion featured a spectacular four-sided tower with a three-story-high inward-curving arch topped by an open pergola[3] that was said to have been visible from almost anywhere in Central Park.

[4] The house rose nine stories, with Victorian Turkish baths below ground level, laundry rooms on the top floor and many Greek marble columns.

[5] The Murray M. Harris organ, designed by Arthur Scott Brook, had four manuals (keyboards) and pedalboard, 74 ranks and 71 speaking stops.

[5] Clark's art collection included works by Eugène Delacroix, Jean-François Millet, Jean-Baptiste-Camille Corot, John Constable, François Boucher and Charles-François Daubigny.

"[3] The editor of The Architect called the mansion "The House of a Thousand Cartouches" and despised the "dolorous and ponderous granite" chosen.