If Mont Alto State Park isn't the smallest state park in Pennsylvania, it's pretty close. It's located on PA Route 233 south of US 30. It appears to be used mainly by locals.
The structure on the left is obviously a picnic shelter. But when built, it was something else altogether. It was the outside of a merry-go-round.
In the early twentieth century, the country was crisscrossed by "interurbans" or rural streetcars. These electric railways often built amusement parks to bolster their ridership. One such park was located here. When it was abandoned, the shell of the carousel was retained and made into the picnic shelter.