There are several classic foliage driving routes in the Granite State, but if I really had to choose one, I suppose it would be the one centred around craggy Mount Monadnock in the southwest. There’s about 130 km (80 mi.) worth of loop along Routes 12, 101, 202, and 123, with quaint, historic towns along the way like vistas from the 19th-century printmakers Currier and Ives, including Keene, Peterborough, Marlborough, Marlow, Troy, Jaffrey, Fitzwilliam, Gilsum, and West Rindge. Highlights include the Cathedral of the Pines; Keene’s Thorne-Sagendorph Art Gallery at Keene State College; the early-19th-century Horatio Colony House; the Town of Swanzey Historical Museum; in Peterborough, the Mariposa Museum of World Culture and the Mondadnock Center for History and Culture; several marvelous nature reserves; and seven delightful covered bridges.
Read more in my post New Hampshire Is Classic New England.