Short answers, pulled from the story.
Fairmount Park is the largest municipal park in Philadelphia, Pennsylvania, covering 2052 acres split into East Park and West Park by the Schuylkill River. The name also serves as a historic label for a wider group of parks once found across the city.
Wissahickon Valley Park in Northwest Philadelphia, Pennypack Park in Northeast Philadelphia, Cobbs Creek Park in West Philadelphia, and Franklin Delano Roosevelt Park in South Philadelphia were all part of the Fairmount Park system. 58 additional parks, parkways, plazas, squares, and public golf courses were also included until Philadelphia Parks & Recreation formed in 2010.
Henry Pratt owned the Lemon Hill estate, and his land had originally belonged to Robert Morris, a signer of the Declaration of Independence. The city purchased the estate in 1844 and dedicated it to the public by ordinance on the 15th of September 1855.
Philadelphia held the 1858 design competition to re-landscape Lemon Hill and Sedgeley for public use. City officials framed the project as the best way to protect the city's water supply.
Fairmount Park contains houses including Mount Pleasant (1762-65), Cedar Grove Mansion (1748-50), Boelson Cottage (1678-84), Strawberry Mansion (around 1783-89), and Sedgeley Mansion, built in 1799 and later demolished in 1857. The Philadelphia Museum of Art administers Mount Pleasant and Cedar Grove Mansion.
Fairmount Park holds a large public art collection built up by the Association for Public Art, founded in 1872 as the Fairmount Park Art Association. Its holdings include the Florentine Lions installed in 1887 and Iroquois by Mark di Suvero, installed in 2007.