The Grand Canyon, one of the world's natural wonders and a UNESCO World Heritage Site, is a mile (1.6 km) deep, 18 miles wide (29km) and 277 river miles (446km) long. Up close, the canyon walls are marked by beautiful patterns of color and erosion, while the immensity of the gorge can be appreciated from any number of stunning viewpoints along the North and South Rims. The park receives over six million visitors a year and can be toured by helicopter, guided hike, ground tour or raft trip down the Colorado River. Park headquarters are at Grand Canyon Village, near the south entrance.