Located atop aptly named Mars Hill, this is one of the oldest astronomical observatories in the Southwest, founded in 1894 by Percival Lowell. Over the years the observatory has played important roles in contemporary astronomy—among the work carried out here were Lowell’s study of the planet Mars and the calculations that led him to predict the existence of Pluto. (Thirteen years after Lowell’s death, Pluto was finally discovered, almost exactly where he had predicted it would be.) The facility consists of outdoor displays, several observatories, and a visitor center with lots of fun and educational exhibits. During the day, there are guided tours every hour between 11am and 3pm; at 10am, 1pm, and 4pm, you can look at the sun through a small telescope that was designed for safe viewing. However, the main attraction is the chance to observe the stars and planets through the observatory’s 24-inch telescope. Keep in mind that the telescope domes are not heated, so if you come up to stargaze, be sure to dress appropriately. There are no programs on cloudy nights.