Edwin Bartlett, a wealthy merchant, subsequently purchased the site and hired Gervase Wheeler to design a house on the property, which was constructed in 1849.

Rockefeller died there in 1922, and his heirs sold it to investors, who turned the house and property into Rockwood Hall Country Club.

[4] Importer and merchant Edwin Bartlett obtained the property around 1848, demolished the farmhouse,[3] and built Rockwood, an English Gothic castle of locally quarried stone.

[2] His residence in Mount Pleasant persuaded his brother, John D. Rockefeller, to build his estate Kykuit in nearby Pocantico Hills.

[11][9] He also hired noted architectural firm Carrère and Hastings to create plans for interior renovation of the house.

[14] Rockefeller also spent $6,000 to repave a 2-mile (3.2 km) stretch of road with macadam from the Vanderbilt Shepard home Woodlea to Sleepy Hollow Cemetery.

[18] In 1914, during the Colorado Coalfield War, the Rockefeller brothers' properties of Rockwood Hall and Kykuit were the site of rioting and potential home invasion.

His funeral took place in Rockwood Hall, with a service by the rector of Saint Mary's Episcopal Church, which Rockefeller regularly attended.

In 1924, Vanderlip purchased 57 acres (23 ha) of Rockwood Hall's riverfront property to add to his estate, Beechwood.

[25] In the following year, the Rockwood Hall club sold 166.5 acres (67.4 ha) of its own land east of Route 9 to John Jr., in order to settle or reduce two of its mortgages.

In 1938, John Jr. purchased Rockwood Hall Country Club and its 220 acres (89 ha) from Chase Bank for $244,374 in bankruptcy court.

In late 1941 and early 1942, John Jr. ordered the demolition of the mansion, coachhouse, greenhouses, powerhouse, barn, chicken house, pigeonhouse, sheds, and boathouse; only excluding the two gatehouses.

Debris was to be dumped into the Hudson River, and care was taken to not damage the property's retaining walls, trees, shrubs, roads, and terraces.

Their father, John Jr., was cautious about the proposal, believing that the site's occupancy would prompt the UN's expansion onto other Rockefeller properties nearby in Pocantico Hills, and possibly even Kykuit, the family's seat.

A low, 4 story corporate headquarters with reflecting pool and fish pond was designed by Architect Edward Larrabee Barnes and Associates.

Laurance had planned to donate Rockwood Hall to New York State, and made the IBM sale to offset the loss of tax revenue to the town of Mount Pleasant.

In the meantime, the state commissioned a study of the river around the property, the Rockefellers granted walking tours for 540 residents, and gave them questionnaires to them to gauge reactions.

Residents indicated on the questionnaires that they preferred passive use of the park: walking trails and a nature center, and no camping or sporting facilities.

[1] New York State subsequently purchased Memorial Sloan Kettering's portion (appraised at $26.8 million[1]) in order to fully own Rockwood Hall.

These halls had mosaic floors, walls wainscoted in American oak, and papier-mâché ceilings with a series of domes, each fitted with five electric chandeliers.

It also had a large fireplace of bright orange and white mosaic tiles, with designs of Italian eagles and foliage, and a circular hearthstone 20 feet (6.1 m) in diameter.

The den nearby had red birch walls and ceiling and a painted frieze, along with a yellow tiled fireplace.

[34] Frederick Law Olmsted designed the landscaped property for William Rockefeller,[2] consisting of hills, dales, woodlands, and meadows.

Two had stone gatehouses on one side of the entrance, while the third, the center gate, only had oak trees around the road, and led to the principle driveway to the stables and mansion.

The drive from the gate to the house took a visitor along a slightly ascending and winding road, through a grove of elms, to the east of Rockwood Hall.

[10] The house's architecture inspired the design of the Sacred Heart Academy in Cincinnati, Ohio, which was built from 1864 to 1867 by Thomas Sargent as a private home for William C. Neff.

[36] In 2014 and 2015, the Stone Barns Center for Food and Agriculture, a nearby non-profit farm, tended sheep and goats in this park.

[37] During the project, a shepherd would rotate the flock every few days through a series of paddocks, coaxing the animals to graze invasive plants like akebia and porcelain berry.

The project gave the center additional land and forage for sheep, and helped control invasive plants and improve soil health.

Local supporters of the project included New York Life, which supplied water, and the nearby retirement community Kendal on Hudson.