The life and work of the Polish patriot and hero of the American Revolution are commemorated here.

Kosciuszko returned to the United States in August 1797 to a hero's welcome after his wounding, capture, imprisonment, and banishment from his native Poland, which was partitioned by three neighbouring powers.

Kosciuszko's secretary, Julian Ursyn Niemcewicz, having been instructed to find "a dwelling as small, as remote, and as cheap" as possible, chose Mrs. Ann Relf's boarding house at the corner of 3rd and Pine Streets in Society Hill.

Here, where Kosciuszko recuperated from his wounds while rarely leaving the house, he was visited by numerous luminaries of the day, including Vice President Thomas Jefferson, architect Benjamin Latrobe, Supreme Court Justice William Paterson, Chief Little Turtle of the Miami people, and Chief Joseph Brant of the Mohawk nation.

At 0.02 acres (0.0081 ha; 870 sq ft; 81 m2), the memorial is America's smallest unit of the National Park System.