This 2,100-mile-long hiking path passes through 14 states from Mount Katahdin, Me., to Springer Mountain, Ga., along the ridges of the Appalachian Mountains. Conceived in 1921 by Benton MacKaye, the trail was completed in 1937. It was designated a National Scenic Trail in 1968. One half mile to the south along the trail is Bears Den, a unique rock formation. The nearby stone mansion of the same name, constructed in 1933, is one of several summerhouses built along the Blue Ridge for wealthy Washingtonians between 1880 and 1940. It has been a hostel and lodge since 1986.