The Mount Airy Forest, in Cincinnati, Ohio, was established in 1911. It was one of the earliest, if not the first, urban reforestation project in the United States. With nearly 1,500 acres (6.1 km2), it's the largest park in Cincinnati's park system. Home of the Stone Steps 50K, MT. Airy is a trail runners paradise in a sea of urban sprawl. Bring your trail shoes as parts can be a little nasty.