While not exactly on the AT and not neccesarily a must see, President Hoover's Retreat in Shenandoah National Park is worth the blueblaze trail to see it.
Rapidan Camp is where Herbert Hoover and first lady came for relaxation during his days in the White House. President Hoover was an avid fisherman and enjoyed the great outdoors and immersing himself in nature and it's beauty. Hoover's Retreat has been designated a national historic landmark.
Of the three buildings still in existence, the Brown House is the only one that has been fully restored inside and outside.
The side trail leading to the camp starts from the AT at Milam Gap at mile 53, 3 miles south of Big Meadows. Take the Mill Prong Trail blueblaze trail for a 4 mile out-n-back hike to a piece of american history.