Most visitors view the canyon from South Rim viewing stations. Considering that it has taken the Colorado River the past 17 million years to carve this wonder out of rock, it seems only fair to take a closer look. Built by the National Park Service in 1924, the South Kaibab Trail takes you to the wonderfully named "Ooh Ah Point" and, for the adventurous, further into the canyon's depths. Plan carefully, heat stroke is no fun. In the northwest corner of Arizona, visitors usually head to South Rim Village (120 kilometers northwest of Flagstaff on route 180) or the North Rim Village. Free shuttle buses service the South Rim in summer months. Ranger-led day hikes and walks take place through out the year .