Four miles west of city center in Lakewood is Green Mountain. The 6,854-foot mesa summit in William Frederick Hayden Park is where the mountains meet the plains. Covered in scrub grasses and shrubs, cacti and yucca, there are no trees. The park is 2400 acres large and linked by hiking trails to nearby landmarks including Dinosaur Ridge and Red Rocks Amphitheatre, world famous for dinosaur tracks and bones and celebrity performing artists, respectively.

A significant prairie dog town occupies the lower western slopes of Green Mountain. Elk, antelope, deer, rabbits, snakes, foxes, and birds live here. For the last four years, Hayden Park has been home to a herd of 250 goats used to help municipal weed management snacking on leafy vegetation in the park.