Wissahickon Valley Park was acquired by the Fairmount Park Commission in 1867. Wissahickon Creek, a tributary of the Schuylkill River, flows twenty one miles through Montgomery and Philadelphia Counties. The Park encompasses 1835 acres and has been a site of settlement since the seventeenth century. The Fairmount Park Commission began acquiring parcels along the length of the Wissahickon in 1868 for the purity of the City river supply. Eventually, the Park extended from the confluence point at the Schuylkill River out to Montgomery County in the Fort Washington Extension added 1915 (which was later transferred to Commonwealth). The Park is one of the first areas to have been designated as a National Natural Landmark (1966). Wissahickon Valley Park is the site of numerous historic properties, public art, WPA structures, historic bridges and distinctive landforms. Currently, the Park consists of 1835.44 acres.