This historic observatory is located atop aptly named Mars Hill and is one of the oldest astronomical observatories in the Southwest. Founded in 1894 by Percival Lowell, the observatory has played important roles in contemporary astronomy. Among the work carried out here was Lowell's study of the planet Mars and the calculations that led him to predict the existence of Pluto. It wasn't until 13 years after Lowell's death that 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 numerous fun and educational exhibits. During the day, there are guided tours every hour between 1 and 4pm, and between 12:15 and 12:50pm, you can look at the sun through a small telescope. 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.