Plush mansion turned hostelry, the Hartness House Inn in southern Vermont is tricked out with all of the amenities you'd expect — canopy beds, fireplaces — as well as one you wouldn't: the remains of an underground astronomical observatory built by a Vermont governor, James Hartness, at the turn of the 20th century. Accessible by a "secret" passage, the space is now a museum open to guests interested in gazing — if not at stars, then at antique telescopes, including the first turret tracking telescope in the country. Hartness House Inn, 30 Orchard Street, Springfield, 802-885-2115, hartnesshouse.com.