The Gateway of the Sun, carved from a solid piece of andesite, is located in the ancient Incan city of Tiahuanaco, in modern day Bolivia. Some researchers have dated Tiahuanaco to 15,000 BC based upon astronomical alignmenments of sighting stones similar to those found at Stonehenge. Tihuanaco is located next to one of the largest inland freshwater lakes in the world, Lake Titicaca. Titicaca's high altitude would have protected it from the great flood which occured with the melting of the great glaciers at the end of the last Ice Age.