Kitt Peak National Observatory was established in 1958 to advance the science of astronomy in the wake of the launch of Sputnik by the Soviet Union. Selected from over 100 potential sites, Kitt Peak was leased from the Tohono O'odham people by the National Science Foundation, and construction quickly began on the 36-inch and 84-inch telescopes (the size is measured by the diameter of the primary telescope mirror). Over the years, many more optical and radio telescopes were added to make Kitt Peak home to the world's largest collection of optical telescopes as well as the largest solar observatory in the world.
Kitt peak is open to the public during the day for tours and exploration of a limited number of telescope observatories, including the Mayall 4-meter telescope, one of the largest optical telescopes in the world. It closes to the general public at 4 p.m. The evening programs are the real treasure here, though, and reservations must be made days or even weeks in advance for these. The night observing programs are only offered during the darkest days of the month when the moon is not in the sky. Programs range from basic astronomy and star observing to more advanced observing through one of the many telescopes on site and very advanced programs that enable the serious amateur astronomer to work with an astronomer to create and leave with digital images of sky objects.
The Advanced Night Observing Program is a great choice for people with a good basic understanding of the night sky and an interest in doing a lot of telescope observing. This program includes a simple dinner, an introductory talk by a staff astronomer, an opportunity to watch the sunset from a great vantage point while getting more orientation to the night sky, and a few hours in an observatory getting to view objects including planets, double stars, star clusters, nebulae, and galaxies. The final treat is the caravan of cars leading back down the mountain with their headlights off to keep from disturbing the observations going on above.
The Kitt Peak Observatory is a national treasure and still one of the premier research facilities for astronomy in the world.
Note that, while visiting the observatory is free, there are fees for tours and the evening sky programs. Find more information on the specific tours available here.