Machu Picchu, located in the Sacred Valley, is an example of the Incas adapting building tactics to the area's geography. While other Pre-Columbian societies built man-made mountains, the Incas focused on the natural geography surrounding them. They used this strategic location to protect it from invasion and also as a source of irrigation. Machupicchu is accessible only by foot or small motorized vehicle. The trail begins at the southern end of town, near the ornate stone gateway known as the Picchuartipass. After about five hours, you'll reach the Sun Gate, where travelers would have risen with the sun to begin their days working in the fields or preparing food. From there, it's another three hours until you reach the End of the World: Lake Titicaca. From the shore, you can see the highest peak in Peru, Mount Pisco (6714 ft), its snowcapped summit visible even during the dry season. In addition to being one of South America's most beautiful places, Machu Picchu is also home to many plants and animals unique to the region. There are over 700 species of plants here, including several types of orchid found nowhere else on Earth. Macchu Picchu is also famous for its large colony of vultures. The birds are among the last links with the ancient culture, since no archeologists are allowed inside the city limits.