It is owned by the Pennsylvania Historical and Museum Commission and operated by the non-profit group, The Friends of Graeme Park.

Graeme Park was constructed in 1722 by Sir William Keith as a summer residence and alternative to his governor's mansion at Shippen House on Second and Spruce Streets in Philadelphia.

A malthouse is a building in which brewers create malt by starting the germination process of barley or other grains.

This malthouse was one of several attempted commercial ventures undertaken by Sir William Keith during his term as governor of Colonial Pennsylvania.

Trade was slowed tremendously and supplies of grain were rotting on the idled ships in the colonial ports in cities like Philadelphia.

Graeme Park was originally called "Fountain Low" by Sir William Keith, its builder and first resident.

He installed decorative devices that were common during the Georgian era, including paneling and refinished several of the interior doors.

Dr. Graeme also commissioned the construction of an outdoor kitchen, laid out a formal garden and began a 300 acres (120 ha) "Deer Park" to make it "a piece of Beauty and Ornament to a dwelling (that any English noble would be proud to have ... by his house."

Graeme Park is confiscated by the Continental Congress due to Henry Fergusson's loyalist sympathies during the American Revolution.

Both of these qualities made him a less than ideal suitor for Elizabeth's hand in marriage and Dr. Graeme forbade that they marry.

He returned to Philadelphia by way of New York City as a loyalist with Sir William Howe commander of the British forces in American.

Fergusson involved his wife in his activities by sending her as a messenger to General George Washington to ask for his surrender and to present a bribe to a major in the Continental Army.

He was found a traitor by the Supreme Executive Council of Pennsylvania and Graeme Park was seized under the Confiscation Act of 1778.

Elizabeth Fergusson may have delivered some letters, for her husband's sake, that called her loyalty into question, but she remained a patriot throughout the Revolution.

Among these were Dr. William Smith,[5] first president of the University of Pennsylvania, Robert Morris known as the financier of the Revolution, and Benjamin Rush, a signer of the United States Declaration of Independence and the man who introduced her to Henry Fergusson.

Their son William was married to Ann Larrett in 1810 and the Penrose built a second farmhouse at Graeme Park for the newlyweds.

Abel and his wife, Sarah Beisel, continued to preserve Graeme Park for future generations.

Since Elizabeth's death in 1801 it has been rumored by the citizens of Horsham, Pennsylvania that the Keith House and Graeme Park are haunted by her ghost.

These local legends have been embraced by The Friends of Graeme Park, who perform annual lantern tours of the Keith House.