Philadelphia boasts one of the oldest, largest and most diverse park systems in the United States. Yet our parks receive scant attention in histories of lanpdscape design and city planning.  In “Counting Trees: The Search for Fairmount Park,” Elizabeth Milroy, author of The Grid and the River: Philadelphia’s Green Places, 1682-1876, will describe the development of Philadelhia’s urban parks in the two centuries after William Penn and Thomas Holme drew public squares on the seminal city plan. Thanks to many hours working in HSP's collections, she uncovered new information and new insights that explain in particular how and why the Schuylkill River valley, anchored by the hill called Fairmount, gained renown for its scenery and why it was later developed as public parkland both in opposition to and in concert with the squares Penn envisioned in his city center.