Rocky Mountain Arsenal National Wildlife Refuge--Once a site where the U.S. Army manufactured chemical weapons such as mustard gas and GB nerve agent, and later leased to a private enterprise to produce pesticides, the Rocky Mountain Arsenal has become an environmental success story. The 27-square-mile Superfund cleanup site, an area of open grasslands and wetlands just west of Denver International Airport, is home to more than 330 species, including deer, coyotes, prairie dogs, and birds of prey. An estimated 100 bald eagles make this one of the country's largest eagle-roosting locales during the winter.

The Rocky Mountain Arsenal Wildlife Society Bookstore is at the visitor center. The U.S. Fish and Wildlife Service offers a drop-in visitor program as well as guided tours. For a guided tour, it's best to call at least a week in advance. Allow at least an hour.