Arizona, United States
There may be bigger observatories in the world, but Kitt Peak National Observatory and the National Optical Astronomy Observatory—both located atop Arizona's Quinlan Mountains, 6,880 feet above sea level—is the most diverse, with 22 optical telescopes and two radio telescopes. Visitors can get their hands on three of the telescopes—a 20-inch and a 16-inch Ritchey-Chrétien telescope and a 16-inch Meade Schmidt-Cassegrain telescope—at one of the open-to-the-public observing programs, which take place every night of the week.
Visit: In addition to the nightly observing programs, guided tours are offered daily at 10 am, 11:30 am, and 1:30 pm. The observatory's closed from July 15 to September 1 for monsoon season.
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