The Grand Canyon is a spectacular destination beyond compare. Located within Grand Canyon National Park in the state of Arizona in the United States, the Grand Canyon is 277 miles (446 km) long, 18 miles (29 km) wide, and over 6,000 feet (1,800 meters) deep. This UNESCO World Heritage Site and Wonder of the Natural World was carved by the Colorado River over an estimated 17 million years. Now, it tells two billion years of geological history through the layers exposed on its walls. Visitors to the Grand Canyon can enjoy the view from a popular viewpoint on the South Rim. Rafting the Colorado River, or descending the walls of the canyon by hiking or horseback-riding are also popular activities. Helicopter tours of the Grand Canyon are also available for tourist willing to splurge. The closest international airports to the Grand Canyon are in Las Vegas, Nevada; and Phoenix, Arizona. From there, visitors can reach the park by car.