My sister is confident this picture's from some where in North West Pennsylvania, USA, but where exactly?
There's not a lot to go on in the photo, but based on the NW Pennsylvania location I'd say it's the Bicentennial Tower in Erie, Pennsylvania.
The staircase is a good match, and the distinctive light shades can be seen around the platform at the base of the tower.
Image taken from the Wikipedia article linked above
Screenshot from Street View