Wisconsin, United States
The University of Chicago's Yerkes Observatory may not have the most high-powered telescopes, but its contributions to science are significant nonetheless. The observatory was founded in the late 1800s by George Ellery Hale, who was one of the first to believe that observatories, instead of housing just a telescope and observer, should also include laboratories devoted to physics and chemistry—the result gave the Yerkes Observatory the nickname "the birthplace of modern astrophysics." The observatory is home to a 40-inch refractor, which is still one of the largest of its kind. The outside is notable as well: The building was designed by Henry Ives Cobb—who decorated the exterior with the signs of the zodiac and the phases of the moon, among other ornamentation—and the grounds were designed by John Olmsted, brother of Frederick Law Olmsted, the famed desingner of New York City's Central Park.
Visit: Free, guided tours are offered on Sundays at 10 am, 11 am, and 12 pm. Weekday tours can be scheduled for $25 for up to five people, plus $5 each additional person. Keep an eye out for scheduled public evening observation sessions, family programs, and parties.
More From Condé Nast Traveler:
The Most Dangerous Foods You Can Eat Around the World
Cemeteries So Beautiful, You Wouldn't Mind Spending Eternity in Them
The Top 25 Cities in the World
Eerily Beautiful Abandoned Places