For many visitors, Colorado is synonymous with one thing: the Rocky Mountains. These rugged giants dominate the Centennial State, and hitting the great outdoors to discover them is pretty much mandatory. Luckily, Colorado tours make exploring these natural wonders easy. Book a full-day excursion to Rocky Mountain National Park, go for a hike at Pikes Peak, plan a day trip to Breckenridge, or discover the highlights of Mesa Verde National Park. But don’t overlook Colorado’s capital: Denver, the Mile-High City, offers plenty of its own must-dos, from trips to the RiNo arts district to food crawls or downtown ghost tours.