Rocky Mountain Arsenal National Wildlife Refuge, located in Commerce City, Colo., is the largest urban refuge in the National Wildlife System in the U.S. Nowhere else can you get the vastness of open prairie with views of the Front Range and the Denver skyline. And the refuge is loaded with a wide variety of wildlife to boot. Many raptors hunt at the refuge with different birds of prey in different seasons. During the winter months, bald eagles, ferruginous hawks and prairie merlins are frequent visitors in the area. Keep an eye out for the merlins catching birds close to their size as meals.