Interesting that Google calls this a park… It’s not a park yet. It’s the abandoned Reading train track, an elevated railway system that cuts through the northern part of Center City. Nature has reclaimed most of the structures up there. See it in its glory before the city cleans it up and turns it into a Highline Park.
I bet you didn’t know you can get lost in nature in Philadelphia. Philadelphia has one of the largest parks within a city. Wissahickon Valley is part of the larger Fairmount Park. Along the trail you’ll find statues, old bridges, dams, waterfalls, a great spots to go bouldering.