The Pittsburgh Botanic Gardens is a nature reserve in Oakdale, PA- located right next door to Settlers Cabin Park. The park opened in early 2015 on a 460 acre plot of land once used for mining and logging, and currently has about 60 acres that was transformed back into pristine nature and open for visitors to enjoy.
This one does require a payment for entry, and those who visit will enjoy a serene hike in nature through several themed zones and unique art pieces.