Colorado covers most of the southern Rocky Mountains and the northeastern region of the Colorado Plateau, as well as the western area of the Great Plains. The states capital is Denver, which is also Colorados most populated city. The areas main port of entry is Denver International Airport which is the 13th busiest in the world. Colarado is well known for its beautiful landscape of mountains, forests, rivers and desert. Hiring a car in Colorado means that you can visit some of the states most popular attractions which include Denver Art Museum and Denver Museum of Nature and Science.